f LIBRARY OF CONGRESS. 



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I UNITED STATES OF AMERICA. * 



THE USE 



OF THE 



STEAM-ENGINE INDICATOR : 



OR, 



Practical Science for Practical Men. 



By Edward Lyman, C. E., 

MEMBER OF THE AMERICAN INSTITUTE OF MINING ENGI- 
NEERS ; PUBLISHER OF THE AMERICAN STANDARD 
OF BOLTS AND NUTS (CHART) ; LYMAN'S 
GEAR CHART, AND UNIVERSAL 
SCREW CUTTING INDEX, 
ETC., ETC. 



PUBLISHED BY THE AUTU&Rr 



NEW HAVEN, CONN, 







Entered according to the Act of Congress, in the year 1874, 

By JEJDWJLMJD JLYMAN, 
In the Office of the Librarian of Congress at Washington. 



Is 



/ 




PUNDERSON & CRISAND, 

Printers, 

New Haven, Conn. 



:• 






cO 



TO THE 
OWNERS AND USERS 

OP 

STEAM POWER, 

WHO ARE ENDEAVORING, BY THE USE OF THE BEST 

KNOW APPLIANCES FOR THAT PURPOSE, 

TO ECONOMISE IN THE 

CONSUMPTION OF FUEL, 

THIS VOLUME IS RESPECTFLLLY DEDICATED, 

BY THE AUTHOR. 



TABLE OF CONTENTS. 



PAGE 

Description of the Indicator 9 

What the Indicator shows 10 

Duties of an Engineer using the Indicator 11 

The different Lines of the Diagram 12 

Brief description of the Diagrams 13 

Importance of Testing the Steam-gauge 21 

Horse-power of Boilers 22 

Rule for Finding Boiler Horse-power 25 

How to take a Diagram 28 

Points to be noted 34 

Effect of the Angularity of the Connection Rod 35 

Taking care of the Indicator 37 

Working up the Diagrams 38 

Eule for Calculating the Horse-power of Steam- 
engines 38 

Position of the different Lines of the Diagrams. ... 47 

General description of the Diagrams 48 

Construction of the Indicator 60 

Importance of Indicating Engines 62 

Theory of the Steam-engine 66 

Heat 68 

Thermometers 72 

Compression and Expansion of Gases 74 



6 TABLE OF CONTENTS. 

Liquefaction 76 

Vaporization 77 

iSurcharged Steam 81 

Boiler Explosions by Surcharged Steam 82 

Expansion of Steam 83 

'Tables of Pressures when using Steam Expansively 87 

Cutting off Steam 92 

The Slide-valve 93 

Diagrams. 97 






PKEFACE. 



In the following pages the author proposes to set 
forth some things which have been done by the "use 
of the Steam-engine Indicator," and hopes thereby to 
make the body of the work conform to the title-page. 
Most writers upon this subject make use of rules, 
formulas, and mathematical matter, which, to the pro- 
fessional man may be acceptable enough, but to the 
busy manufacturer and the practical engineer these 
formulas are dry reading. Said a large manufacturer 
to me once in the City of New York, " I care very 
little for the scientific principles upon which these 
things are based; results are what I want." And so 
it is with the busy men of these times : satisfy them 
of the results, and that is what they will pay liberally 
for; they are willing to leave the discussion of the 
scientific part to experts. Satisfy any sane man that 
he is burning two pounds of coal where one pound 
would do his work, and advise him of the best means 
under the circumstances of bringing about the reduc- 



8 PREFACE. 

tion, and so far your duty is done and you are justly 
entitled to the measure of praise of him " who makes 
two blades of grass grow where one grew before." 

This work plainly shows the difference between 
good and bad diagrams, as they are selected from 
the regular practice of the author, with reference to 
the special business in hand, and any person who is 
operating with steam as a motive power, may peruse 
these pages with pleasure and profit. To the student 
of steam and mechanical engineering, this volume will 
aid him in his researches in a marked degree, and 
will hold its interest to the end, being as it is a prac- 
tical work of to-day ; and, to the general reader, an 
hour spent with this book will well repay you by its 
addition to your stock of general information, of what 
it has to say of the principles of the leading great 
prime mover of the Nineteenth Century. 

E. LYMAN, C. E. 
New Haven, October, 1874. 



THE USE 



OF THE 



STEAM-ENGINE INDICATOR 



-♦♦♦- 



The Steam-engine Indicator is a small instrument 
(see Frontispiece) which may be attached at any time to 
the cylinder of a steam-engine, at either end or both, 
by a pipe usually about half an inch in diameter. Then, 
by attaching the cord of the Indicator to some part of 
the engine having motion coincident with the piston, 
and placing a piece of paper upon the cylinder of the 
Indicator, admitting steam through the pipe, and then 
applying the pencil of the Indicator to the paper, a card 
or diagram is traced. This is done when the engine is 
regularly working, either loaded heavily or light, mak- 
ing no delay to the manufacturing business to which the 
engine is attached. By this card, which is called the 
"" Indicator card" or diagram, the working condition 
of the engine is positively shown as it can be in no 



10 THE USE OF THE 

other way. In fact, as has been said, " it is the stethe- 
scope of the physician, revealing the nature of the 
disease in the vitals of the patient." 

By this card is shown the horse-power of the engine 
under any given load, so that if there are two or more 
parties using power from the same engine, by taking 
a card with each one's work attached, it can be shown 
just how much each party is using. It shows the con- 
dition of the valves, whether they are set right or not- 
serious losses of power occur from this cause ; whether 
the piston or valves leak, or whether the passages are 
large enough or not ; the amount of steam consumed 
by the engine in a given time, from which may be 
estimated the amount of water evaporated, and the 
amount of coal consumed to evaporate that water. A 
first-class engine, if working properly as it should, 
ought to furnish one horse-power with a consumption 
of from 2i to 3 pounds of good coal per hour ; but 
many engines at the present day are using more than 
double that amount, showing a flagrant waste. 

The writer proposes to show in this work a series 
of diagrams of good and bad forms, that have been 
taken in his own practice, and in connection with them 
to point out the course pursued by him to correct the 
bad ones and give the results that have been attained, 
in order that the readers may form their own opinions 



STEAM-ENGINE INDICATOR. 11 

and be the better able to judge of what course to 
pursue if they are in any way desirous of reducing 
their expenditure for fuel — at all times dear enough, 
and in the present depressed state of manufacturing 
interests, a matter for very serious consideration. 

In what may be said in these pages the writer will 
endeavor by all means to avoid personalities of every 
kind, hence the names of the makers of engines re- 
ferred to will be omitted, the purpose being to deal 
exclusively with principles and not engender strife 
among the different builders in a work of this public 
character. If the writer himself is consulted on the 
matters of which this book treats, he will give his 
opinion, after examining the engine, of the best course 
to be pursued under the circumstances, reference being 
had to all the points in the case. Sometimes it becomes 
the engineer's duty to recommend a new engine ; some- 
times a new cylinder, and possibly some modification 
of the valve gearing or valves. In some cases, by very 
slight adjustments which may be done in half an hour's 
time by an intelligent mechanic, the engine may be put 
in proper condition and a saving of from 5 to 15 or 20 
per cent, effected. In many cases engines are set up in 
a bad way, having too much or too little speed, and, by 
making changes in the speed, the power may be very 
materially effected with economical results. It is irr- 



12 THE USE OF THE 

possible to state all cases. Almost every application 
of the Indicator pesents different conditions — some of 
them novel — for the consideration of the engineer and 
proprietor. The writer has a very large number of 
diagrams that he has taken himself from different en- 
gines, besides others that have come into his possession 
in various ways : some viciously bad, others as good as 
could be expected or as need be desired, showing very 
economical results. The several lines of the diagram 
are designated in the following manner : 

The Atmospheric Line. 
The Perfect Vacuum Line. 
The Admission Line. 
The Steam Line. 
The Expansion Line. 
The Exhaust Line. 
The Counter-pressure Line. 
The Compression Line. 

In non- condensing or high-pressure engines there 
is no vacuum, consequently the diagram is as it should 
be, all above the atmospheric line. In low-pressure 
engines the counter-pressure line should come down to 
18 or 14 pounds below the atmospheric line. I have 
cards that I have taken that do this, and where the 
Indicator shows the same vacuum in the cylinder that 



STEAM-ENGINE INDICATOR. 13 

the vacuum gauge shows in the condenser, a result 
which, where the vacuum is reasonably low, is all that 
could be desired. 

Diagram No. 1 is a theoretically perfect diagram, 
showing the expansion curve correct, with the steam 
cut-off at one-fifth the stroke. An approximation to 
this perfect diagram is all that can ever be attained in 
practice with an Indicator; but the nearer to it the 
diagrams come the better is the engine from which 
they are taken. Two points may be especially noticed: 

1st. That engine will give the greatest horse-power, 
with the least consumption of fuel, which unites the 
highest initial pressure with the lowest terminal pres- 
sure. 

2d. The vice to be especially deprecated is that 
technically known among engineers as wire drawing, 
in which the steam line runs along with possibly an 
undulatory movement ; starting low, perhaps 30 pounds 
or more below the pressure in the boiler, and ter- 
minating very nearly as high as it started. An engine 
showing such a diagram will yield a small amount of 
power, but it will consume a large amount of fuel ; and 
here may possibly be the source of an explosion. The 
boiler pressure is not even approximately reached in 
the cylinder, by possibly 30 or 40 pounds ; the engine 



14 THE USE OF THE 

does not do its work satisfactorily ; the safety-valve 
weight is moved out on the lever, and the boiler is 
over-crowded and has to suffer, when the real cause 
of all the difficulty is with the engine and its attach- 
ments. 

Engines for different purposes will, in the good 
judgment of the engineer, require to show somewhat 
different diagrams. For instance, driving a stationary 
engine for running a train of rolls in an iron or steel 
rail mill will be quite a different business from driving 
a propeller on board of a steam vessel ; the former will 
have a very fluctuating load, say from 100 to 600 horse- 
power, requiring the constant action of a complete gov- 
erning apparatus, while the latter will work right up 
to the actual power of the engine and keep right along 
at a uniform rate of power, subject to occasional adjust- 
ments at the hands of the engineer on the watch. For 
ship purposes the writer believes there is great merit in 
the double cylinder or compound engine, that is, work- 
ing the steam at high pressure in one cylinder and from 
that into another at low pressure, either with or without 
an intervening reservoir ; and this may be brought into 
more general use for stationary purposes, but as yet it 
has not been very much used. The writer knows of 
one instance where a party offered a neighbor of his 



STEAM-ENGINE INDICATOR. 15 

ten dollars a year for his exhaust steam, from a high- 
pressure engine, for a term of years. This he turns into 
a cylinder which he works below the pressure of the 
atmosphere, and it furnishes him ample power to drive 
a machine shop of some magnitude, I should say not 
less than five nor more than ten horse-power. It is, by 
all means, the most economical steam-power within the 
present knowledge of the writer. 

There are many claimants for favor among the 
various styles of engines, and most of them have some 
points of excellence ; but there are so many conflicting 
statements in reference to them that parties wishing 
to purchase, not having personal knowledge of them, 
may well be in doubt as to the most economical kind 
to procure ; but, in such cases, let every judicious man 
ask to see the Indicator diagrams and when produced, 
if he is not familiar with them himself, let him refer 
them to some one who is. Let each engine stand on 
its own merits, for the Indicator is a sure and unfail- 
ing witness, and in the hands of a careful and expe- 
rienced man will tell no wrong stories. To the present 
owners of engines I would say that the periodical ap- 
plication of the Indicator to your engines will be found 
to result in a uniform reduction of your fuel bills, and 
be a very general source of satisfaction to all having 
direct connection in any way with your steam-power. 



16 THE USE OF THE 

Diagram No. 2 was taken from an engine of 22 in. 
bore by 15 in. stroke, by the writer. It was a plain 
slide-valve engine, of the ordinary kind. I recom- 
mended an independent adjustable cut-off, which was 
put on at an expense of about $300. This engine, when 
this diagram was taken, required an evaporation of 
about 200 gallons of water per hour. 

Diagram No. 3 was taken from the same engine 
after the above change was made, and doing the same 
work. It now required an evaporation of 150 gallons 
of water per hour— a plain case of saving 25 per cent. 

Diagram No. 4 was taken from an engine similar 
to the one No. 2 was taken from, and under similar 
circumstances. The same change was recommended 
and the same results reached, as shown by diagram 
No. 5, which was taken after the change, to wit, about 
25 per cent. The 25 per cent, saving in coal, in each 
of the above cases, amounted to about 50 pounds per 
hour, or 500 pounds per day of ten hours, which, 
at $8 per ton, amounts to $2 per day, or say $600 a 
year. 

Diagram No. 6 was taken from a steam yacht that 
the owner supposed was in perfect working order until 
the application of the Indicator. It is a very bad 
diagram and shows late admission, the engine not 
getting its steam until the piston had passed the middle 



STEAM-ENGINE INDICATOR. 17 

of its stroke. This diagram was from the lower end of 
the cylinder, and the valve was balanced; there was 
lost motion in the connections, and the weight of the 
valve kept it down, thus it did not open the port 
until it was a fourth of a revolution at least too late, 
Remedy — Take out the lost motion and re-set the valve. 
Result— A gain in power, with the same steam, of 
about 20 per cent. 

Diagrams No. 7 are a pair, taken from both ends of 
one of a pair of low-pressure engines. They show 
characteristics peculiar to the class of engines to which 
they belong. Both engines show similar diagrams, 
and they are bad. They show back-pressure of about 
35 per cent. At the time these diagrams were taken 
the vacuum gauge showed 25 inches in the condenser,, 
which is equal to about 12-J- pounds, while in the cylin- 
der only 5 pounds vacuum on the crank-end and (> 
pounds on the out end, is obtained. The trouble with 
these engines, in this particular, is, that the exhaust 
passages from the cylinder to the condenser are insuf- 
ficient; they are too small and too long, and very 
crooked. The steam passages also are too small. 
When these cards were taken the steam pressure, per 
gauge in the boilers, was 75 pounds. One of the cards 
only reaches 54 pounds, and the other only 50 pounds. 
Correcting the foregoing evils on these engines, which 



18 THE USE OF THE 

can probably be done at an expense of about $10,000, 
will produce a saving of upwards of 50 per cent., 
which will amount to about 1,200 pounds of coal per 
hour. The engines are used about twenty hours per 
day, which would effect the saving, in round numbers, 
of about 12 tons per day, equal, at $8 per ton, to $96, 
or about $29,000 annually ; a waste which, when con- 
templated in the light of these times, is something 
-enormous. 

Diagram No. 8 was taken by the writer from a small 
engine of 6 in. bore by 12 in. stroke, and is somewhat 
peculiar. The engine was running at a high rate of 
speed — 225 revolutions per minute — and doing very 
little work ; yet it shows a high initial and a low ter- 
minal pressure, fulfilling the conditions of a first-class 
engine. The high speed at which it was taken caused 
the movement of the Indicator piston to be somewhat 
vibratory, so much so that the vibrations of the expan- 
sion line cause it to cross the compression line. All of 
the movements are in correct time, and it is a good 
diagram. It was taken at the suggestion of the builder, 
in the presence of the owner, in order to ascertain if it 
was working all right, and the result proved highly 
satisfactory. 

Diagram No. 9 was taken from an engine that was 
noticed to be using more steam than formerly. It was 



STEAM-ENGINE INDICATOR. 19 

an engine with an independent cut-off, and the trouble 
with it was that when cutting off short the construction 
was such that the cut-off passed by the opening in the 
main valve and opened the port for steam a second 
time. The card on this engine, as it was running, re- 
quired the use of 315 pounds of coal per hour. The 
writer had the cut-off adjusted to follow a little farther, 
when 

Diagram No. 10 was taken, which is very good; 
the same engine, with this card, only requiring 150 
pounds of coal per hour. A plain case of saving up- 
wards of 50 per cent.; whereas it was using about 1^ 
tons of coal in ten hours, it now uses about three- 
fourths of a ton. 

Diagram No. 11 was taken by the writer from an 
engine of 54 in. bore and 36 in. stroke, low-pressure, 
direct-acting, upright. It shows trouble with both the 
steam and exhaust passages. When this card was 
taken the vacuum gauge showed 25 inches of vacuum, 
equal to about 12-J- pounds, but only 8 pounds was 
obtained in the cylinder, and that just at the end of 
the return stroke. The pressure of steam in the boiler 
at the same time was 60 pounds, but the pressure in the 
cylinder only reached 25 pounds — a failure to come up 
of 35 pounds. The writer with others, in consultation 
with the owners, recommended a new cylinder of 44 in. 



20 THE USE OF THE 

diameter, and a differently constructed valve-gear. The 
change was made under the supervision of the writer 
at an expense to the proprietors of about $5,000. By 
this diagram the coal required was about 1,700 pounds 
per hour. 

Diagram No. 12 was taken from the new cylinder 
when it was doing precisely the same work as the old 
one, when No. 11 was taken, and it only required a 
consumption of 770 pounds of coal per hour, making a 
saving of about 55 per cent. The actual facts, as taken 
from the coal account for a two-weeks run with each 
cylinder, show a saving, when reduced to dollars and 
cents, in favor of the new cylinder, of $60 every 24 
hours ; the engine is worked double turn, and being 
worked to its maximum duty for say 200 clays in each 
year, gives a saving to the proprietors of $12,000 
annually. The new cylinder disposed of the use of 
three boilers, each 15 ft. long by 5 ft. diameter, with a 
dome 4 ft. high by 3 ft. diameter, each boiler having 
forty-two 4-in. tubes, and made lighter firing on the 
remaining boilers. 

Diagram No. 13 was taken from an engine of a 
first-class make, high-pressure. It had been running 
some time, been excessively loaded, and had become 
worn. The effect of the wear, here shown, is, that 
the movements are behind time. There is no steam- 



STEAM-ENGINE INDICATOR. 21 

lead, and, besides, the piston advanced fully one-tenth 
of the stroke before the maximum pressure was reached 
in the cylinder. If the exhaust had opened a little 
sooner, the counter-pressure line would have run lower; 
all of which would have enlarged the area enclosed 
by the diagram, and so have shown a development 
of more power than is now shown. The remedy is 
easy of application, which is, to renew the lifters, and 
make them of the proper length to lift the valves in 
time. The writer examined this engine with the Indi- 
cator, together with others at the same time, for the 
same company, and directed repairs to be made on 
them similar to the above, about six months ago. He 
has received notice to come and examine them all 
again, together with others which have since been 
started by the company. 

Another application of the Indicator, of very great 
importance, is to test the steam-gauge. This is done 
when the Indicator is attached, by putting the engine 
on the center, admitting steam to the Indicator, and 
seeing whether the Indicator and steam-gauge agree 
or not. Most steam-gauges, of any spring construction, 
vary from the correct pressure. 

Diagram No. 14 was taken for the above purpose, 
and was found to agree perfectly — a result seldom 
found, a common deviation being from 1 to 5 pounds, 



22 THE USE OF THE 

sometimes 8 pounds, and in one instance as high as 
15 pounds out of the way. Quite enough, in some 
cases, to account for disaster to the boiler. 

Diagram No. 15 shows the result of attaching a 
condenser to a first-class cut-off engine, of high-pres- 
sure, and working it low-pressure. This card shows 
62 per cent, below the atmospheric line, on a develop- 
ment of twenty-nine horse-power, which shows a credit 
to the condenser of seventeen horse-power — less the 
amount taken to work the air-pump, which probably 
does not exceed one horse-power. 

Diagram No. 16 was taken quite recently by the 
writer, and shows a pretty bad state of affairs. After 
a complete summing up it shows the astonishing fact 
that the engine from which it was taken is using 12 
pounds of good coal per horse-power per hour ; a waste 
of fully 75 per cent., and this 75 per cent., in this case, 
amounts to $7.80 per day. 

With reference to horse-power, the rule used in this 
work is that which was used by Watt, viz., 33,000 
pounds raised one foot high in a minute ; and just here 
a few words upon horse-power will not be out of place, 

A boiler of good evaporative efficiency will evapo- 
rate, under favorable circumstances, from 8 to 12 
pounds of water with one pound of good coal. Now, 
how much horse-power is this ? Let us see. Take fcr 



STEAM-ENGINE INDICATOE. 23 

example Diagram No. 15. Here we have a develop- 
ment of twenty-nine horse-power and a required evapo- 
ration of 780 pounds of water per hour, giving to each 
horse-power 27 pounds of water per hour. Now, if 
this boiler is competent to evaporate 10 pounds of water 
with 1 pound of coal, which doubtless it is, it will give 
2fo pounds of coal per horse-power per hour. 

Again, take Diagram No. 16, where it was found 
that the engine used 12 pounds of coal per horse-power 
per hour, and assuming that the boilers evaporate 10 
pounds of water with 1 pound of coal, as the writer 
believes they do, then there is used 120 pounds of 
water per horse-power her hour. As was said in refer- 
ence to Diagram No. 16, that there was a waste of 75 
per cent. , it will now be seen that 27 pounds of water 
in the former case is 22^ per cent, of 120 pounds in 
the latter, the whole difficulty being entirely with the 
engine. 

A cubic foot of water weighs about 62-£ pounds, and 
assuming that evaporated as equal to one horse-power 
(see Reports of Committees on boiler horse-power, Jour- 
nal of the Franklin Institute, December 1873, page 397), 
then the 120 pounds in the latter case is equal to 192 
per cent., while the 27 pounds in the former case 
amounts to 43 per cent., again making the former 22£ 
per cent, of the latter. 



24 THE USE OF THE 

The foregoing is sufficient, in this place, to show 
what the writer desires : that so far as the consumption 
•of fuel is concerned, a horse-power in one engine is a 
very different thing from what it is in another, and to 
direct the attention of steam users particularly to this 
-difference, that the power in both cases is precisely the 
same, only that one engine wastes steam to the amount 
of 75 per cent, while the other utilizes it fully. At this 
point I trust my readers will see and appreciate the 
Use of the Steam-engine Indicator, which opens 
to the view T of owners of steam-power such facts as 
have here been stated. 

Said an engineer of much ability to me recently, 
*" You may run a 100 horse-power boiler up to its full 
capacity, and I will work all of that steam through a 
ten horse-power engine," thereby meaning that it was a 
comparatively easy matter to waste 90 per cent, of the 
steam. In the case of Diagram No. 16, cited above, 
there are two 100 horse-power boilers, being run nearly 
to their full capacity, and only doing thirty horse- 
power work. The committee of the Franklin Institute, 
previously referred to, having had the subject of boiler 
horse-power under consideration for about three years, 
were discharged, having seen no good reason for chang- 
ing the English standard — that of one cubic foot of 
water evaporated into steam, at atmospheric pressure, 



SLEAM-ENGINE INDICATOR. 25 

as one boiler horse-power ; that is to say, a boiler hav- 
ing heating surface enough, combined with grate sur- 
face enough, to evaporate ten cubic feet of water in one 
hour is equal to a ten horse-power boiler, or is a com- 
mercial ten horse-power boiler. 

Now, what amount of heating and grate surface is 
necessary to evaporate a cubic foot of water per hour ? 
On this point makers disagree. Most men will consider 
the foregoing a very large allowance for one horse-pow- 
er ; but, going back again to the English practice— and 
they have allowed in some instances one square yard of 
effective heating surface, and one square foot of fire 
grate for one horse-power, that is, to evaporate one 
cubic foot of water per hour — and assuming this to be 
correct, then you may vary either of them at pleasure, 
within certain limits. For instance, you can enlarge 
your heating surface and reduce the size of the fire 
grate. 

RULE FOR FINDING THE HORSE-POWER OF STEAM BOIL- 
ERS BY USE OF THE ENGINEERS SLIDE RULE. 

Bute. — Reverse the slide and set the area of effective 

heating surface, in square yards, on C, to the area of 

fire grate, in square feet, on A, and looking to the left 

or right, as the case may be, the first two divisions 

3 



26 THE USE OF THE 

of the same value that coincide with each other are the 
horse-power of the boiler, when thus arranged. 

Example. — Suppose you have 16 square yards of ef- 
fective heating surface in a boiler, with a fire grate of 
25 square feet, and you wish to know the most suitable 
rate to work the boiler at ; then on the slide rule, with 
the slide inverted, set 16 on C, against 25 on A, and, 
looking to the left, the first two divisions of the same 
value on A and C, that coincide with each other, are 
those of 20, and they represent the horse-power of the 
boiler, viz., twenty horse-power; or, in other words, 
according to the English standard, a boiler having 16 
square yards of effective heating surface, and 25 square 
feet of fire grate, will evaporate 20 cubic feet of water 
per hour. Again, suppose that a boiler is intended to 
drive a thirty horse-power engine, but it has only 25 
square yards of surface and the area of the fire grate is 
required, then, using the slide rule, invert the slide 
(which is, simply changing ends with it), and set 30 on 
C against 30 on A, and, looking to the right hand, you 
will find against 25 yards of surface on C, the answer to 
be nearly 36 square feet of fire grate upon A ; and, in 
like manner, against any number expressing the square 
yards of effective heating surface on C, you will find 
the number of square feet of fire grate most suitable for 
the given power upon A. In short, the inverted line C 



STEAM-ENGIKE INDICATOR. 27 

represents a table of thirty horse-power boilers, with 
various areas of surface, and the line A represents a 
table of areas of fire grates corresponding to those sur- 
faces : 

A 1 30 1 Fire grate 1 31 [ 34 | 36 | 39 | 45 

| 30 | Heating surface . | 29 | 261 | 25 | 23 | 20 

The inverted slide rule, when thus set, exhibits at 
a glance the various ways in which a thirty horse-power 
boiler may be set up. It will be seen that any one of 
these three principal data respecting boilers may thus 
be found when the other two are given by any workman 
in the possession of a slide rule.* 

Now, if any of my readers demur from the data 
here given, as to the quantity of heating surface or 
grate surface necessary to evaporate one cubic foot of 
water per hour, all that is necessary for them to do is 
to change the amounts of either, or both, and the calcu- 
lations will then be just as easily made on the slide rule 
as with the given amounts. Suppose, for example, that 
you assume half a square yard of heating surface and 
half a square foot of fire grate, then one half of the 
above results would be the correct data, or whatever 
fraction of the data above given you assume, the 

* See advertisement of slide rules and books at the end of this 
volume. 



28 THE USE OF THE 

amounts are readily computed on the slide rule by 
direct proportion. 



HOW TO TAKE A DIAGRAM. 

CONNECTING THE INDICATOR TO THE CYLINDER. 

If the cylinder has not been drilled for the Indicator, 
have it drilled. If it is a horizontal engine, on the top 
side of the cylinder, at both ends, as near the ends as 
possible, so as to be sure that the piston does not cover 
the hole, and tap the holes out with a half -inch pipe tap 
and then we can screw the Indicator fittings right into 
the cylinder, or put in a nipple and attach the Indicator 
to that, and when we are done the holes can be plugged 
up by screwing in a half -inch gas-pipe plug. Then the 
engine can always be indicated at any time; or the holes 
may be drilled in the cylinder heads, and angular con- 
nections used; or, diagrams may be taken from the 
cocks in the cylinder where the water is drawn off, but 
the diagram is not as sure to be reliable. In any case 
the opening should never be less than half an inch 
in diameter, and be as short and direct as possible, 
avoiding all unnecessary bends ; the object being to 
have the pressure in the Indicator exactly the same as 
it is in the cylinder of the engine, for upon this pres- 
sure all our calculations are based. It is desirable that 



STEAM-ENGINE INDICATOR. 29 

the Indicator stand upright, as shown in the engraving, 
although cards can be taken with it standing at an 
angle. It is also necessary that it be set up firm, for, if 
it stands loosely, the cord may pull it from its original 
position, and thus destroy the accuracy of the diagram. 
If the engine is vertical, it may be drilled in one side 
of the cylinder, close to the top and bottom ; at the bot- 
tom end it will lime to be drilled in the side, while the 
top may be drilled in the cylinder cover, or the tallow- 
cup may be removed and the Indicator inserted in its 
place. Good judgment will soon decide where the best 
place to connect with the cylinder is. 

MOTION OF THE PAPER CYLINDER— CONNECTING THE 

CORD. 

Having preparations made as described for attach- 
ing the Indicator to the cylinder, the next thing is to 
provide a motion to partially rotate the paper cylinder 
of the Indicator, which is perfectly coincident with 
the motion of the piston, and for this purpose the 
motion of the piston must be reduced to about 4 inches, 
more or less. The Indicator will take a card nearly 
6 inches long, and it is desirable it should be as loug 
as possible; but if the motion is too long it is quite 
liable to cause trouble, by making the paper cylinder 
strike the stops, which must be avoided or the diagram 



30 THE USE OF THE 

will be a failure. If the motion of the engine is slow 
enough to admit of it, a diagram 4 to 4J- in. long, 
will be a very good length, but if the motion of the 
engine is fast it will have to be taken shorter. (See 
diagram No. 8, which was taken at a speed of 225 
revolutions per minute.) 

If the engine is a beam-engine, or has vibrating 
arms connected in any manner with the cross-head, as 
some condensing engines have for working the air- 
pumps, then, by going towards the beam center, or 
towards the centre on which [the arms vibrate, near 
enough to get a movement of 4 or 4} in., more or 
less, there you may attach your cord; then set the 
engine piston in the middle of its travel and lead oft 
your cord and fix a carrying pully in such a position 
that the cord will be at right angles to whatever gives 
it motion. After this you may carry it to the Indicator 
in any direction you please. Then fix a running-loop, 
so you can readily shorten or lengthen your cord, and 
you can hook it to the cord on the paper cylinder when 
ready; but in a large majority of cases no such ready 
means of getting the motion as has been described will 
be found, and the engineer will sometimes have to tax 
his ingenuity sufficiently to get up a means of reducing 
the motion in a horizontal engine, of say 4 ft. stroke, to 
4 in. The writer has had occasion to do two such cases 



STEAM-ENGINE INDICATOR. 31 

within the week this was written, and it was done in 
this way : Cut a narrow strip of board, say 1 in. thick 
and 4 in. wide at one end, and 3 in. wide at the other, 
and 10 or 12 feet long, according as there is room. 
Make a hole in both ends, and make the wide end fast, 
by a bolt through the hole, to anything that is handy; 
or something temporary may be set up for the purpose, 
so that the board will lay horizontal. Then erect a 
board frame under the point of the board near the bed 
of the engine, for the board to slide back and forth 
on and not fall down, and connect the board to the 
cross-head by means of a connection made of a piece 
of iron, say 1 in. by J^ in., which may be connected 
by one of the set screws which are in the guides for 
tightening up the shoe to the cross-head, and the 
other end to the board by a bolt 1 — care being taken to 
so fit all the bolts that there will be no lost motion, 
and then see that the center on which the board 
vibrates is in the middle of its travel. Then make a 
hole in the vibrating board, near enough to the center 
of vibration to get the 4 in. of motion. Follow the 
directions previously given, for leading off the cord 
at right angles to the board when the piston is in the 
middle of its travel. In some cases it may be more 
convenient to suspend the vibrating board from a 
point over head. All cases cannot be described, but 



32 THE USE OF THE 

each individual case has to be considered according to 
its situation and peculiar conditions. 

All the time that you have been preparing these 
things for your motion, &c, it is presumed that the 
engine is in motion doing its regular daily duties. It 
should be a point with the skillful engineer never to 
hinder the manufacturing business to which an engine 
is attached, but to let it be known that he can make 
his examinations and indications without any hindrance 
to the proprietors. The engine must be stopped long 
enough to insert the Indicator cocks in the cylinder 
and connect the motion to the cross-head. The writer 
has done this repeatedly in three minutes. Now direct 
the engineer in charge to start up, and as the engine 
moves slowly see that your connections are all safe 
and right, and everything clear, then you can attach the 
Indicator to the cock on one end of the cylinder, by 
means of the screw coupling, and your cord to the 
source of its motion, and now you are ready to 

FIX THE PAPER 

on the paper cylinder. For this purpose remove the 
paper cylinder from the instrument; secure the lower 
edge of the paper, near the corner, by one spring, 
then bend the paper round the cylinder, and insert 
the other between the springs. The paper should be 



STEAM-ENGINE INDICATOR. 33 

long enough to let each end project at least half an 
inch between the springs. Take the two projecting- 
ends with the thumb and finger and draw the paper 
down, taking care that it lies on the cylinder smooth 
and tight, and that the corners are even, then replace 
the cylinder. The paper should be of a good quality, 
without any ruling upon it. The pencil may be a No.. 
4, and whittled down so as to screw into the socket 
provided for it in the parallel motion. With the 
paper on, and the pencil properly pointed and in its 
place, the motion of the cord all right, and some relia- 
ble person to count the revolutions of the engine per 
minute, you may proceed to hook on the cord and 

TAKE THE DIAGRAM. 

First open the stop- cock fully and let steam into 
the Indicator, then turn it off in the direction which 
opens communication between the under-side of the* 
piston and the atmosphere; apply the pencil to the 
paper and it will draw the atmospheric line. Then 
remove the pencil from the paper an instant while- 
you open the cock fully again, and apply the pencil 
to the paper and take the diagram. You can hold 
the pencil to the paper during one revolution, or more r 
as you please. If the engine has a fixed cut-off and a 
constant load, and the steam keeps at the same pressure 



34 THE USE OF THE 

it will trace the diagram nearly in the same line all 
the time; but if it is a variable cut-off, controlled by 
the action of a governor, and a variable load, it will 
rarely make two alike. The writer has cards taken 
from variable cut-off engines, where the pencil was 
kept to the paper for some time, that are nearly all 
-covered within the area of the largest with the pencil 
markings, from the perfect vacuum line to the highest 
point reached. Now shut off the steam from the Indi- 
cator and unhook the cord, and take off the diagram 
by slipping it from under the springs, and note on the 
back of it as many of the following facts as you are 
in possession of, viz. : 

The date, hour, and minute of taking the diagram. 

The name of the owner, and which engine if he 
has more than one. 

Which end of the cylinder. 

The pressure of steam, as per guage in the boiler. 

The number of revolutions per minute. 

The diameter of the bore of the cylinder. 

The length of stroke. 

The scale of the Indicator. 

The name of the builder of the engine. 

The kind of valve. 

The size of the steam and exhaust pipes. 

Whether the throttle is wide open or not. 



STEAM-ENGINE INDICATOR. 35 

The kind of governor, if any. 

On a condensing engine, the vacuum per gauge. 

The temperature of the discharge. 

The size and kind of the air pump, and how it is 
driven. 

The highth of the barometer. 

A description of the boiler. 

The amount which the waste room in the clearance 
and passage would add to the length of the cyl- 
inder. 

The amount of coal consumed per hour. 

The temperature of the feed water, and the quantity 
used. 

And any other special items that may appear im- 
portant. 

You can now take more diagrams from the same end 
of the cylinder, and then change the Indicator to the 
other end and take cards from there. The cards from 
both ends of the cylinder will not be alike ; this is due, 
if there were no other cause, to the angularity of the 
connection rod which gives a higher rate of speed to 
the piston as the crank passes the semi-revolution the 
farthest from the cylinder. In a direct-acting engine, 
of from 15 to 33 per cent., the difference varying accord- 
ing to the degree of angular vibration of the connection 
rod. In beam-engines the highest rate of speed of 



36 THE USE OP THE 

piston, from this cause, will be at the top, or when the 
crank is passing the lower semi-revolution. The reader 
will please take special notice of this on the pair of 
diagrams No. 7, taken from both ends of a cylinder 
of a direct-acting engine, the left hand diagram was 
taken from the out-end of the cylinder, or the end 
farthest from the crank, where the slow motion is 
found ; the right hand diagram was taken from the 
crank end, or the end nearest to the crank, where the 
fast motion is found, and you will notice the difference. 
The steam rose about 4 pounds higher than in the other, 
and the piston moving rapidly caused the pressure to 
fall about 5 pounds lower than the other diagram to the 
point of exhaust. The extra velocity of the piston 
also affected the counter-pressure line, which does not 
fall so low as the left hand diagram, and makes the 
right hand diagram more pointed than the left. The 
slower motion of the piston on the left-hand diagram 
maintains the pressure on the expansion line, and 
gives more time for the exhaust, which carries the 
counter-pressure line lower and makes a fuller and 
better shaped diagram. The average effective pressure 
on the left hand diagram is 36 pounds per square inch,, 
and on the right hand diagram 31i pounds. The steam 
on these diagrams is pretty badly wire drawn, on 
account of the throttle-valve being partly closed, and 



STEAM-ENGINE INDICATOR. 37 

the points of cut-off, although not well denned, are 
somewhat different in time — one following about -ft of 
the stroke, and the other over tV. These last named 
causes also affect the shape of the diagram, and, taken 
with the former, produce the result seen in Diagram 
No. 7. 

If, now, you have taken what cards are necessary 
from both ends of the cylinder, shut the stop-cocks 
and take off the Indicator and lay it away in the box. 
Then stop the engine for about two minutes, take out 
the cocks and insert the plugs, and disconnect your 
temporary motion and have the engine got under way 
again at once, making no delay to the manufacture. 
Next, take care of your Indicator. The Indicator will 
not work well unless it is kept in good order. When 
used it becomes filled with water, which will rust and 
weaken the spring, and the steam often contains im- 
purities and grit, some of which may lodge in the 
Indicator. Unscrew the cover of the cylinder case, 
and draw off the upper ferrule with the pencil move- 
ment and the piston and spring attached, empty the 
water from the cylinder, and clean and dry all the 
parts and replace them, oiling the cylinder and other 
parts with a few drops of the best oil. Wipe it up 
clean and lay it away in the box, and it will be ready 
for use the next time you want it; but if you neglect 



38 THE USE OF THE 

to care for it as above, it will soon become weak in the 
springs and rusty and sticky, and finally fail to give 
any indications that can be relied upon. 

WORKING UP THE DIAGRAMS. 

TO ASCERTAIN THE HORSE-POWER OF THE ENGINE. 

As has been previously stated in this work, on page 
22, the horse-power of an engine is that used by 
Watt, viz., 33,000 pounds raised one foot high in one 
minute, or 33.000 foot pounds, and this is now em- 
ployed as the unit of measurement of the actual horse- 
power of steam-engines, and the rule for calculating it 
is simply this : 

RULE FOR CACULATING THE HORSE-POWER OF STEAM- 
ENGINES. 

Multiply the mean effective pressure on one square 
inch of the piston in pounds, by the area of the piston 
in square inches, and that product by the speed of the 
piston in feet per minute, and divide by 33,000, the 
quotient is the horse-power of the engine. Example — 
You have an engine of say 10 inches diameter of bore 
of cylinder, and 2 feet length of stroke, and it runs 100 
revolutions per minute, and you have 32 pounds mean 
effective pressure on one square inch of the piston, what 



STEAM-ENGINE INDICATOR. 39 

is the horse-power? Area of 10 in. piston = 78-ftfo sq. 
in. ; one revolution of a 2 ft. stroke is equal to 4 ft. r 
which, multiplied by 100, gives 400 ft. as the speed of 
piston per minute, this, with the mean effective pressure 
given, makes out the requisite data 

78.54 x 32.X 400 = 3 f 

33,000 F 

or, 78.54 

multiplied by 32 

15708 
23562 



2513.28 
multiplied by 400 

divided by 33,000 \ 1005312.00 / 30M the horse-power. 



\ 1005312.00 / 
/ 99 V 



15 

The above data may be found as follows : The area 
of any piston, by the use of the engineers slide rule 
(see advertisement at end of volume), by setting 78.54 on 
the C line, against 10 on the D line, then against any 
other diameter on D, is its area in square inches on C* 
It may also be found in tables of areas. 

* In the book, descriptive of the engineers slide rule, there are 
full directions given for getting the horse-power of engines, and 
when it is once understood, and the data are given, the horse- 
power of any engine can be told in 10 seconds, the writer himself 



40 THE USE OF THE 

The length of the stroke is easily measured, and this 
doubled and reduced to feet, and multiplied by the 
number of revolutions per minute, gives the speed of 
piston in feet per minute. Our mean effective pressure 
we may assume, or if we know the boiler pressure and 
the point of cut-off we may demonstrate mathemat- 
ically the mean pressure by the use of hyperbolic logar- 
ithms, and when arrived at it will be an approximation 
to the actual facts. 

THE ONLY MEANS KNOWN 

to steam engineers to arrive at this mean effective pres- 
sure with certainty is by the "use of the steam-engine 
Indicator." The diagram shows the pressure on one 
square inch of the piston at all points of its stroke, and 
from this we must calculate the average or mean pres- 
sure. The piston of the Indicator is made of a 
diameter sufficient to give it an area of one half a 
square inch, and the springs are made of a tension 
suitable to make them agree with a scale correspond- 
ing to which they are marked, and with this scale the 
vertical highth of the diagram is measured, and its 
figures represent the pressure on one square inch of 

can do this, and will be pleased to satisfy any incredulous person 
on this point who will favor him with a personal interview and 
put the question and give the data. 



STEAM-ENGINE INDICATOR. 41 

the steam-engine piston. Now, the average mean pres- 
sure is found in this way: Divide the diagram into 
any number of equal parts (the writer usually uses 
ten), by lines drawn perpendicular to the atmospheric 
line. Then draw lines parallel with the atmospheric 
line, in spaces of five pounds, according to the scale 
of the Indicator, up as high as the boiler pressure 
(which record you will find on the back of your dia- 
gram) and below as far as the perfect vacuum line. 

IF IT IS A CONDENSING ENGINE, 

the diagram should be partly below the atmospheric 
line.* It is of no consequence what the character of 
the diagram may be — whether it is high up or low 
down on the lines you have just drawn, or whether it 
is most wasteful like diagram No. 11, or economical 
like No. 12 — for the purpose of ascertaining the 
power exerted we have merely to measure its included 
area, and so get the mean pressure on one square inch 
during the stroke which this area represents. The 



* I have diagrams taken from a condensing engine on which the 
counter-pressure line is 5 pounds above the atmospheric line at 
its lowest point, when, at the same time, there was 18 in. of vacuum 
in the condenser. You may ask, how could a man afford to run 
such an engine as that? He didn't know it, and supposed it was 
all right until these cards were taken, when the fact was shown 
that the engine was wasting 76 per cent, of its steam. 
4 



42 THE USE OF THE 

writer uses a planimeter and measures the area of the 
diagram first above the atmospheric line, next below it; 
adding the two areas together and divide this sum by 
the extreme length of the diagram, the quotient is the 
mean highth, which, multiplied by the scale of the 
Indicator, gives the mean pressure. But a plain and 
simple way of doing is to measure very carefully the 
highth in each of the ten vertical divisions and add 
them all together, and point off the right hand figure. 
This will give you the mean highth, which again multi- 
plied by the scale gives the mean pressure in pounds per 
square inch. Thus you have all the data from which 
you can calculate the horse-power of the engine, ac- 
cording to the rule previously given. 

THEN THE BACK PRESSURE 

can be found by measuring. If it is a condensing en- 
gine, the distance between the perfect vacuum line 
and the counter-pressure line, or if it is a high-pressure 
or non-condensing engine, by measuring the distance be- 
tween the atmospheric line and the counter-pressure 
line. 

THE PERFECT VACUUM LINE 

will vary according to location and condition of the 
atmosphere, and for certain purposes the engineer 



STEAM-ENGINE INDICATOR. 43 

should note the highth of the barometer and locate the 
perfect vacuum line accordingly ; but for the purposes 
of this book I have assumed 15 pounds as the perfect 
vacuum point below the atmospheric line, and divided 
the diagrams off into atmospheres of 15 pounds each. 

THE CONSUMPTION OF STEAM. 

For this purpose ascertain how much the clearance 
and steam passage way add to the length of the cylin- 
der at one end, and add a proportionate quantity to the 
length of the diagram, by a line drawn perpendicular 
to the atmospheric line at the proper distance from the 
admission line. Then ascertain the point in the stroke 
at which the steam is released, and the pressure in the 
cylinder at that point. Multiply this pressure, meas- 
ured from the line of perfect vacuum by the sectional 
area of the cylinder in square inches, and the product 
by the length of the stroke in inches up to the point 
at which the steam was released, including the addi- 
tion for the clearance and passage way, and divide by 
14.7 and the quotient will be the number of cubic inches 
of steam, at the pressure of the atmosphere, discharged 
from the cylinder at a single stroke. If the valves do 
not leak, and there is no water with the steam, the 
cubic contents of the cylinder, multiplied by the pres- 
sure at the point of cut-off, should equal the cubic 



44 THE USE OF THE 

contents multiplied by the pressure at the point of 
exhaust, and in a compound engine the cubic contents 
of each cylinder, multiplied by the pressure at the 
point of exhaust, should give the same result. Multi- 
ply this by the number of strokes in an hour, and 
divide the product by 1728, to reduce the cubic inches 
to cubic feet, and the quotient again by 1700, to reduce 
the steam at atmospheric pressure to water, and the 
result will be the number of cubic feet of water used 
per hour. Multiply this by 62.5 for pounds, and divide 
the product by 8.33 for wine gallons. The supply of 
water to the boiler will need to be greater than the 
quantity thus ascertained, and the excess required will 
correspond with the loss from all sources, such as 
leakage, priming, blowing off, and radiation from the 
cylinder and pipes where the water of condensation 
does not flow back into the boiler. Having found in 
the foregoing manner the amount of steam consumed 
per hour, and reduced it to water in pounds, you can 
assume, if you please, that one pound of good coal will 
evaporate ten pounds of water per hour in a good 
boiler, and dividing by ten, will give you the pounds 
of coal consumed per hour, and if you know just how 
much is burned you can compare. Now, if you divide 
the pounds of coal by the horse-power found by the 
card, you will have the pounds of coal per horse-power 



STEAM-ENGINE INDICATOR. 45 

per hour, and if it is over three there can be a saving 
made on that engine by some means. 

TO ASCERTAIN IF THE STEAM VALVES ARE TIGHT. 

Draw the correct expansion line, and for this purpose, 
after having added the proper amount to the admission 
end of the diagram for clearance, divide the distance 
up to the point of cut-off into any number of equal 
parts. In our theoretic diagram No. 1, it is divided into 
two parts. Then continue spaces of the same distance 
to the end of the diagram, and if it does not come out 
even make one line beyond the diagram. Draw the 
perfect vacuum line at the proper distance below the 
atmospheric line, and measure from it with the Indica- 
tor scale to the steam line. Number the vertical lines, 
commencing at the first one from the admission end, 
and if the point of cut-off comes, as in our diagram 
No. 1, at two, then to find the point where the curve cuts 
the third line divide the number of pounds found upon 
the Indicator scale as above by three and multiply the 
quotient by two, and the product is the highth of the 
intersection measured with the scale from the perfect 
vacuum line as before. Mark it, and proceed to the 
fourth line. Now divide by four, and multiply by two, 
and mark the point on the fourth line, and so on to the 
end, always dividing by the number of the line where 



46 THE USE OF THE 

you are seeking the location of the curve, and multiply- 
ing by the number of the line at the point of cut-off. 
Then trace in the curves— the more numerous the 
divisions the more accurate will have been the work. 
Having drawn this correct expansion curve, see if 
the diagram terminates very much above it; if it does, 
the steam valves probably are not tight. If the dia- 
gram falls below it, then the piston or exhaust valves 
leak. Having the diagram drawn in this manner, or 
worked up, you have found from it the pressure on 
the piston at every point of the stroke, the average 
mean pressure throughout the stroke, and the horse- 
power expended, also the back pressure, or the 
amount of power expended in forcing out the ex- 
haust, how near the boiler pressure is reached in the 
cylinder, at what time in the stroke the highest pres- 
sure is reached and how well it is maintained, at what 
point and what pressure the steam is cut off, whether it 
is cut off quickly or whether it is wire drawn, also at 
what point in the stroke the exhaust opened and closed, 
and the pressure at these points, also the pressure aris- 
ing from compression of the exhaust, also the steam 
lead, the amount of steam consumed and water evapo- 
rated, and the amount of coal burned to evaporate that 
water, and if the steam and exhaust valves and piston 
are tight. The Indicator shows faithfully, and only 



STEAM-ENGINE INDICATOR. 47 

shows the pressure on one side of the piston in its for- 
ward and backward movement, and in doing this it has 
described a peculiar shaped figure. The causes which 
have determined that shape must be arrived at by a 
process of reasoning, and the ability to judge correctly 
of the causes which have produced a certain form is no 
mean attainment, and to the student of engineering 
nothing can be more profitable than the careful study 
of the diagrams contained in this work, as they have 
been taken from engines in actual use at no very remote 
date ; and now let us refer to some of them and con- 
sider. 

THE DIFFERENT LINES OF THE DIAGRAM. 

THE POSITION OF THE LINES. 

The atmospheric line is the horizontal line in all the 
diagrams at 0. The perfect vacuum line is the third 
line below 0, marked 15, strictly 14.7, more or less, ac- 
cording to the highth of the barometer. The admission 
line, diagram No. 1, is the vertical line at the left hand 
end. The steam line is the horizontal line at the top, 
and on this diagram is continued for ^ of the 
stroke. The expansion line commences where the 
steam line ends, or at the point of cut-off, and in this 
case is a hyperbolic curve and continued to the end of 



48 THE USE OF THE 

the diagram. The exhaust line is the short vertical 
line at the right hand end. The counter-pressure line 
in this diagram is the same as the atmospheric line. 
The compression line is not shown, but it is the ending 
of the counter-pressure line and the commencement of 
the admission line. The perfect vacuum line is very 
rarely drawn by the Indicator, but is drawn by hand, 
although the writer has diagrams where a very near 
approach to it is made. 

ON DIAGRAM NO. 2, 

beginning at the commencement of the stroke, at the 
right hand end, the admission line starts at 10 pounds 
pressure, and rises vertically to about 27 pounds, when 
the piston moves, after which the pressure rises a trifle 
until the piston has moved about -fa its stroke, when 
the velocity of the piston increasing the pressure com- 
mences to fall and continues to fall to the point where 
the exhaust valve opens at about ■$& of the stroke. 
The steam in this diagram was cut off by lap on 
the valve at -f %, but it is not shown at all, and, strictly 
speaking, there is no expansion line in this diagram. It 
is all steam line, of very bad character, clear to the 
opening of the exhaust. The exhaust line continues 
from the point of its opening to the end of the stroke, 
falling at a small angle from the perpendicular until 



STEAM-ENGINE INDICATOR. 49 

the motion of the paper commences to return, and at 
this point begins the counter-pressure line, which falls 
away to the atmospheric line at the first tenth of the 
return stroke, and continues on the atmospheric line 
until it reaches the point of - } % of the return stroke r 
when the valve closes the exhaust and the compression 
line commences and takes a diagonal course upward to 
10 pounds pressure, to the point of commencement of 
the admission line, which is the point where we com- 
menced our description of this diagram. The reader 
will have no difficulty in following these descriptions, 
as the diagrams are divided vertically into five pound 
spaces and longitudinally into ten divisions, each space 
representing -fa of the length of the stroke of the 
engine. 

DIAGRAM NO. 3, 

taken from the same engine after an independent cut- 
off had been put upon it, shows a different form. The 
admission line commences at 5 pounds pressure and 
rises vertically to about 43 pounds, when the steam line 
commences and rises a little and falls again before the 
first tenth is reached, and continues to fall to the sec- 
ond tenth. This falling of the pressure, from the first to 
the second tenth, is caused by the gradual closing of 
the cut-off valve, which is fully closed at the second 



00 THE USE OF THE 

tenth, and from here, in this diagram, commences the 
expansion line, which runs to the opening of the 
exhaust at -&% of the stroke. The exhaust line here is 
nothing, being nearly horizontal and only T Jo of the 
stroke long. The counter-pressure line commences at 
the beginning of the return stroke, and falls away to 
about 1 pound above the atmospheric line, at the first 
tenth of the return stroke, and then follows parallel, or 
nearly so, to about -nfj, when the exhaust closes and the 
compression line begins and runs to the five-pound point 
at the place of beginning. 

DIAGRAM NO. 4. 

The admission line commences at the left hand end, 
at the point of 10 pounds pressure, and rises vertically 
to about 23 pounds, when the piston advanced about 
Tthj of the stroke and the pressure rose during the 
same time to about 26J pounds, and from that point 
commences to fall and falls to about 16 pounds at -ft- 
of the stroke, when the main valve closed, which caused 
a slight fall of pressure to the point of exhaust which 
is not very marked; but the exhaust line falls verti- 
cally to the point of 5 pounds pressure when the 
counter-pressure line commences and falls gradually 
to to of the return stroke, and then runs along at about 

1 pound pressure falling slightly to about -$>%, when 



STEAM-ENGINE INDICATOR. 51 

the compression line commences and raises the pressure 
to 10 pounds to the place of beginning. 

DIAGRAM NO. 5 

is similar to No. 3, but in this the cut-off is at about -nf - 
of the stroke. The horse-power developed, as shown by 
this diagram, is 31, and on No. 3 it was 29£ ; the 
average mean pressure being on No. 5, 14.r - pounds, 
and on No. 3, 14.- ] 1 - pounds per square inch. 

TN DIAGRAM NO. 6 

the engine did not get its steam until the piston had 
passed about - x % of its stroke at about 78 pounds 
pressure, and then the cut-off closed it at about -flfe, 
and the pressure fell off to 60 pounds, when the ex- 
haust and counter-pressure line all went into one, and 
sneaked along down to 15 pounds above the atmosphere 
at the lowest point. iUtogether it is about as bad a 
diagram as one ever need expect to see. 

ON THE PAIR OF DIAGRAMS NO. 7. 

First, the right hand one : The admission line com- 
mences at 35 pounds above the atmospheric line, the 
steam valve is behind time, and the piston moves on 
about ythj of its stroke before the highest pressure, 55 
pounds, is reached at about ^ the stroke, when the 
pressure commences to fall and the steam-valve is 



52 THE USE OF THE 

closed at about -ft of the stroke. The steam expands 
to about 13| pounds at the end of the stroke, at 
which point the exhaust opens and the counter-pres- 
sure runs down to 5 pounds below the atmosphere 
at -fif$ of the return stroke and remains there until ■£$ 
is reached, when the compression commences and the 
pressure rises to 35 pounds, the place where. the admis- 
sion line began. 

THE LEFT HAND DIAGRAM. 

The steam-valve opens for admission at a pressure 
of 44 pounds, and immediately the pressure falls to 
34 pounds ; then rises again at about T Ju of the stroke 
to nearly 50 pounds, and follows at that pressure for a 
little more than -£$, when the pressure commences to 
fall. When at $fo it has fallen to about 45 pounds, the 
point where the steam-valve closes, the expansion line 
now runs to the end of the diagram and the exhaust 
opens and the pressure falls vertically for a short dis- 
tance, when the counter-pressure commences and the 
pressure falls at #o of the return stroke to 6 pounds 
below the atmosphere, and keeps there until -fifo is 
reached, when compression begins and runs the pres- 
sure up above the point of admission to the point of 
beginning, forming the loop seen at the left hand end 
of this diagram. 



STEAM-ENGINE INDICATOR. 53 

DIAGRAM NO. 8. 

In this diagram there seems to be no admission line; 
but starting at 50 pounds pressure, which has been 
reached by compression, the pressure falls at once to 
20 pounds at about T ou of the stroke. Then the piston 
of the Indicator recoils slightly, and falls again and 
crosses the compression Jine at about #0, and falls to 
about 2-J- pounds ; then rises again to 4 pounds, at about 
ttht, and from there gradually falls until it crosses the 
atmospheric line at -^JV, and falls to a little more than 
1 pound below the atmospheric line, to the point of 
exhaust at about -nfo, when the atmosphere comes in 
and raises the pressure to a little more than 1 pound 
above the atmosphere, which gradually falls until -ft of 
the return stroke is reached, when the compression 
begins and carries the pressure up to 50 pounds, the 
place of beginning. In fact when this card was taken 
the engine was run by the compression. In this stroke 
it seems not to have taken any live steam at all, which 
is a characteristic of this engine. When the speed is up, 
and the steam is not wanted, it shuts it all off; and 
when it takes steam, what is taken is right up to boiler 
pressure. The writer has seen this engine supersede an 
ordinary slide-valve engine, and save 75 per cent, of 
the fuel required by the old engine, which, after all, 
was not very old, having been run only about two and 



54 THE USE OF THE 

a half years. This diagram was taken at a speed of 
225 revolutions per minute. (See page 18.) 

DIAGRAM NO. 9. 

The admission line commences at the right hand 
end, at a point about 6 pounds above the atmosphere, 
and rises vertically to a little above 35 pounds when 
the piston moves, the pressure still rising slightly until 
about jthr of the stroke is reached, when the cut-off 
valve commences to close and the pressure commences 
to fall and falls to the point at which the cut-off is 
closed — in this case, nfo of the stroke. It is slightly 
noticeable on the diagram. Then expansion com- 
mences, and the pressure continues to fall to 4 pounds 
at -f-J-Q of the stroke, when the cut-off passes by the 
opening in the main valve and admits steam to the 
cylinder the second time, the pressure rising gradually 
to 23 pounds at ■&- of the stroke and remaining until 
the exhaust opens at ■$&, the exhaust line running ver- 
tically clown to 10 pounds, when the counter-pressure 
commences and the pressure falls to 1 pound at the 
first tenth of the return stroke, and gradually approach- 
es the atmospheric line until the compression com- 
mences at iifo of the return stroke and runs the pres- 
sure up to 6 pounds to the place of beginning. This 
card shows a development of 284- horse-power, and the 



STEAM-ENGINE INDICATOR. 55 

cut-off valve was set to cut off the steam at 2 inches 
from the commencement of the stroke. The cut-off 
was then adjusted so as to cut off at 3 inches, when 

DIAGRAM NO. 10 

was taken. This is a tolerably good diagram, and is so 
similar to others that have been described that it need 
not be explained at this time. It shows a development 
of 29f horse-power, which is 1} more horse-power than 
No. 9, with over 50 per cent, less steam. 

DIAGRAM NO. 11 

is an aggravated case of wire-drawing. (See page 19.) 
The admission line commences at the left hand end, at 
about 4 pounds below the atmospheric line, and rises 
vertically to 25 pounds, and this pressure is continued 
to about -, L o% of the stroke when the pressure commences 
to fall and falls to 7 pounds above the atmosphere at 
i% of the stroke, when the valve is closed by lap ; the 
pressure still further falls to 2% pounds at the opening 
of the exhaust at almost the end of the stroke, and the 
pressure falls vertically to 3 pounds below the atmos- 
phere when the counter-pressure commences and the 
pressure falls gradually to 8 pounds at -j a % of the return 
stroke, when compression commences and carries the 
pressure up to 4 pounds below the atmosphere, to the 



56 THE USE OF THE 

place of beginning. The point of cut-off could not be 
determined at all if it were not known. This is a fair 
specimen of a diagram that could be taken from thou- 
sands of engines that are running in this country to-day, 
and in every such case they are wasting fuel for their 
owners to from 25 to 75 per cent. Diagrams of this 
character have been dismissed by experts, as subjects 
not fit for consideration ; but whenever the writer meets 
such diagrams he will endeavor, by all means in his 
power, to vanquish them and bring about such changes 
as will make the engine take a diagram that will show 
a good degree of economy and not a flagrant waste. In 
this case the engine had a thorough overhauling, and a 
new c}dinder and valve gear, and passages better adapt- 
ed to its wants. When it had been got in good running 
condition 

DIAGRAM NO. 12 

was taken. This is a good diagram. Commencing at 
the right hand end the admission line starts at 5 
pounds above the perfect vacuum line, and rises ver- 
tically to 34 pounds, when, as the piston moves, the 
pressure rises to 35 pounds and the steam line follows 
to about j£o of the stroke, when the valve closes and 
the expansion line commences ; and here you may see 
a first-class expansion line. The steam expands to 
5 pounds below the atmosphere, at the end of the 



STEAM-ENGINE INDICATOR. 57 

stroke, when the exhaust opens and the counter-pres- 
sure commences, and the pressure falls gradually to 
nearly the perfect vacuum line at -nfo of the return 
stroke, when the compression carries the pressure up 
to 5 pounds above the perfect vacuum line, to the place 
of beginning. That engine cannot be improved upon 
very much. (See page 20.) 

DIAGRAM NO. 13. 

In this diagram the admission commences at 1 
pound above the atmosphere and the piston moves at 
the same time. The pressure rises gradually to 55 
pounds at -nj of the stroke, and at -^ it is up to 57 
pounds ; the admission line may be said to have ended 
at tV- The pressure in the boiler at the time this card 
was taken was 60 pounds, so it will be seen that it is 
a first-class diagram, excepting in the time of the 
movements of the valves. The steam line is continued 
with a slight fall of about 1 pound to -pfe of the stroke, 
when the valve closes and the expansion line com- 
mences, and the steam expands to 35 pounds pressure 
at the end of the stroke, when the exhaust opens and 
the pressure falls at once to 24 pounds, when the 
counter-pressure line commences and the pressure falls 
to about 1 pound at j% of the return stroke and con- 
tinues nearly parallel with the atmospheric line to the 



58 THE USE OF THE 

end at 1 pound above the atmosphere, the place of 
beginning. There is no compression line on this dia- 
gram. 

DIAGRAM NO. 14 

has been fully explained at page 21. 

DIAGRAM NO. 15 

was taken from the same engine that No. 13 was taken 
from, with a condenser attached and working low-pres- 
sure. The admission line commences at the left hand 
end, at 10 pounds below the atmosphere, and shows 
the steam-valve behind time nearly the same as No. 13. 
(This diagram was taken from the opposite end of the 
cylinder.) The pressure runs to 38 pounds above the 
atmosphere, at too of the stroke, when the steam- valve 
closes and the expansion line commences, and the 
steam expands to 5 pounds below the pressure of the 
atmosphere when the exhaust opens and the counter- 
pressure commences and falls, at the first tenth of the 
return stroke, to nearly 10 pounds below the atmos- 
phere, and runs back to the end of the stroke, at that 
highth, to the place of beginning. There is no com- 
pression line in this diagram. When this diagram was 
taken the vacuum, per gauge in the condenser, was 23 
inches, which is equal to about 11 -J- pounds, and on the 



STEAM-ENGINE INDICATOR. 59 

diagram it is 10 pounds. A very fair result. (See page 
22.) 

DIAGRAM NO. 16 

is another aggravated specimen of wire-drawing. The 
admission line commences at 2 pounds above the at- 
mospheric line, and rises vertically to 20 pounds, and 
from there, at a small angle, reaches 27 pounds, when 
the piston of the Indicator recoils and rises again, and 
at -A- the stroke is at about 19 pounds pressure when it 
commences to fall and falls in a sickly manner to the 
point of exhaust at nearly the end of the stroke, the 
pressure having fallen to 5 pounds above the atmos- 
phere. The exhaust line runs clown the pressure to 
about 2| pounds, when the counter-pressure line com- 
mences and the pressure falls to a little less than 1 
pound at -^ of the return stroke, and remains there 
until -nfo of the return stroke is reached and the com- 
pression line commences and carries the pressure up to 
2 pounds, to the place of beginning. This engine had 
a slide-valve, an independent cut-off, and a throttle 
governor ; but you cannot tell from the diagram where 
the cat-off or the main valve closed. The cut-off closed 
at -ftfe of the stroke, and the main valve probably 
closed at about -ffifo. The counter-pressure line is fair; 
but upon the whole it is a bad diagram. (See page 22.) 



60 THE USE OF THE 

GENERAL REMARKS. 

THE CONSTRUCTION OF THE INDICATOR. 

The Indicator was the invention of Watt, who 
attempted to keep the invention for his own exclu- 
sive benefit, as he was a large manufacturer of engines, 
and by indicating them in private was enabled to so 
improve upon them as to give him an advantage over 
other makers who knew nothing of his cherished 
secret ; but it was impossible for him to keep it secret, 
and it became known to the trade and was manufac- 
tured and sold. Win. McNaught, of Glasgow, manu- 
factured one form, which consisted of a paper cylinder, 
similar to the one shown in this work (see frontispiece), 
which received its motion from a cord attached to the 
engine, as described in this work, page 29. The steam- 
cylinder of these Indicators was necessarily of great 
length, in comparison with the one shown in this work, 
and the springs also had to be correspondingly long, 
and their weight, with the piston and pencil attach- 
ment, when put in motion suddenly, produced a mo- 
mentum which would carry the pencil up past the true 
pressure, and then it would recoil and vibrate up and 
down in such a violent manner as to produce a figure 
upon which very little reliance could be placed, except 
for slow motions and low pressure of steam, when 



STEAM-ENGINE INDICATOR. 61 

15 pounds above the atmosphere was ail that was used, 
and a piston speed of 240 feet per minute ; but when a 
pressure of 100 pounds became common, and cut-off 
engines were introduced, and speeds of piston of 400 
to 600 and 800 feet per minute, and motion of 200 to 
300 revolutions were used, the above described Indi- 
cators were not to be relied upon. In fact it was im- 
possible to indicate one of these high-speed and high- 
pressure engines with them. There was an Indicator 
constructed by the firm of Maudslay & Field, on the 
same general principles as have been described, but 
differing from McNaught's in outside appearance. 

THE INDICATOR USED BY THE WRITER 

is know as " Richards' Parallel Motion Indicator" and 
was invented by Mr. C. B. Richards, of Hartford, Ct. 
It has been manufactured in London by Elliott Broth- 
ers, which fact has given rise to the notion in some 
places that it is an English invention. They are manu- 
factured in this country by the " American Steam 
Gauge Co." of Boston, Mass. The invention by Mr. 
Richards of this Indicator, may justly be said to be 
one of the great improvements of the age ; as for the 
reasons previously given the old style of Indicators 
are wholly useless on the great majority of engines 
of the present day. This Indicator, with proper 



62 THE USE OF THE 

management, will work equally well on fast or slow 
speeds, on high or low pressures, as is shown by the 
diagrams in this work. They have been used successful- 
ly in England and in this country, on locomotives mak- 
ing their regular trips with express trains on the roads, 
which is sufficient evidence of the reliability of the in- 
strument. The difference between this and the old style 
of Indicator consists in this, having a short and strong 
spring and a short movement of piston, both are made 
very light with considerable section of cylinder, and 
an arrangement of levers for multiplying the motion 
of the piston, and a parallel motion for carrying the 
pencil, in such a manner that the diagram is described 
in the same way and about the same size as by the 
old style of Indicator. It is in every respect a first-class 
instrument. 

THE IMPORTANCE OF INDICATING ENGINES. 

There probably never was a time in the history of 
the manufacturing interests of this country when the 
importance of indicating steam-engines was greater 
than it is now. Manufactures are depressed, fuel is 
high, and a giant combination has its mercenary hand 
on the principal coal-fields of this country, and when it 
would seem that the laboring classes and manufacturers, 
many of whom are out of business, should be supplied 



STEAM-ENGINE INDICATOR. 63 

with fuel at fair rates, the price of coal has been 
steadily advanced from the first opening of the season 
to the present time. What is the remedy for this ? 
Economy in the use of fuel is certainly one remedy. 
How shall we economize further? Every manufac- 
turer knows precisely how much coal he is using — he 
has good reason to. He has to pay the bills. Nothing 
could furnish better evidence to his astonished senses 
than those periodically recurring coal bills, with manu- 
factured goods falling, and the price of coal rising. 
He may know positively the amount of coal used, but 
very few know the amount of power which they de- 
rive from that amount of coal. Let every manufac- 
turer who would economize in his coal expense have 
his engines examined by some expert engineer with an 
Indicator, and see how much power he is using, and 
then let him see what amount of coal he is using per 
horse-power per hour. It should not exceed 3 pounds, 
and might be considerably less. The writer has indi- 
cated several engines recently that have run as high 
as 9 pounds, 9-J- and 12 pounds, and in one instance as 
high as 18 pounds per horse-power per hour. What 
price ought any man to pay for such an engine as 
that ? Why, it is dear at a gift. The writer knows of 
engines that have wasted $100,000 worth of fuel, where 
the original cost of the engine did not exceed $25,000. 



64 THE USE OF THE 

Who will attempt to say that such an engine would 
not have been dear at a gift? And this is not an isolated 
case. There are many such. A great majority of the 
engines in this country to-day are using twice as 
much coal per horse power per hour as would suffice 
to furnish the same power with a first-class machine. 
If an engine will not furnish one horse-power with the 
consumption of 3 pounds of coal per hour, then the 
quicker it is thrown away the better for the party 
having the coal bills to pay. But a man has on his 
hands an engine, and he is advised that it is wasting 
his fuel to the extent of 25, 50, or perhaps 75 per 
cent., and he thinks he cannot afford to make any 
change, what can he do ? There can be something 
done with it. Perhaps a new cylinder, or a new 
valve-gear, or condenser (if it was high-pressure). 
That will cost him less at first than he would have 
to pay for fuel at the same time, which might be 
saved by the change the first year, and when it is thus 
changed, although he may not have a strictly first- 
class engine in every particular, he will be in a condi- 
tion to save money enough to buy one with when the 
times are more propitious. But people have been hum- 
bugged. They have tried appliances that have been 
promised to save a certain per cent, and they have 
failed. One man has a frictionless valve, another a 



STEAM-ENGINE INDICATOR. 65 

balance-valve, another a patent packing, another a> 
self-regulating damper, another a feed-water heater r 
and a multiplicity of other things, all of which are 
first-rate in their proper places. And the venders of 
these patents will very deliberately tell you that they 
will save 25 per cent. Now, does any sane man believe' 
that 25 per cent, of the power of a twenty horse- 
power engine is expended in driving a slide-valve in 
its worst form ? By all means have a balance- valve ;. 
but do not expect 25 per cent, saving from that source 
alone. If you do, you will be disappointed. I know of 
one engine that was fitted with a frictionless valve, and 
a saving of 25 per cent, claimed for it, and I also know 
that the frictionless arrangements lie in the scrap-box 
in that engine-room at the present time. The thing 
may have had merit in it, but too much was claimed 
for it, and it has fallen into disuse. Many things have 
turned out in a similar manner. Get an honest man, that 
is competent to indicate your engines — one that will 
report all the facts which he finds, and advise what to- 
do under the circumstances — and when you are advised 
of the true state of the case, then you can act upon it. 
when you see fit. The engine which diagram No. 11 
was taken from had been indicated before, but the per- 
son employed, if he knew how bad it was, did not 
advise the proprietors of the waste of steam going oa 



66 THE USE OF THE 

there. The most charitable construction that can be put 
upon it is, that he didn't know a good card from a bad 
one. I trust the reader is now fully impressed with the 
fact, that before a discussion of the economical merits of 
any given engine can be entered upon, we must first 
know what its comparative economy is, and for this 
purpose we will assume as a starting point 3 pounds 
of coal as sufficient for one horse-power per hour. Now, 
is our engine using more, or less than this? I have 
read of engines being run with less than 2 pounds of 
coal per horse-power per hour, but I have never seen 
one that I know of. I have seen a number using from 9 
to 18 pounds per horse-power per hour. You know the 
amount of coal used, find out the horse-power and 
divide. And now let us examine the 

THEORY OF THE STEAM-ENGINE. 

THE STEAM-ENGINE 

is a machine for extracting mechanical power from 
heat through the agency of water. Heat is one form 
of mechanical power, or, more properly, a given quan- 
tity of heat is the equivalent of a determinate amount 
of power ; and as heat is capable of producing power, 
so power is capable of producing heat. The nature of 
the medium upon which the heat acts in the production 



STEAM-ENGINE INDICATOR. 67 

of power— whether it be water, air, metal, or any other 
substance — is immaterial, except in so far as one sub- 
stance may be more convenient and manageable than 
another. But, with any given extremes of temperature, 
and any given expenditure of heat, the amount of 
power generated by any given quantity of heat will be 
the same whatever be the nature of the substance on 
which the heat is made to act in the generation of the 
power. And just in proportion as power is generated 
will heat disappear. We cannot have both the heat 
and the power ; but as one is transformed into the other, 
so will the acquisition of one entail a proportionate loss 
of the other, and this loss cannot possibly be prevented. 
It has been explained previously in this work that, as 
in all cases in which power is produced in a steam- 
engine, there must be an excess of pressure on the steam 
side of the piston, or, in other words, the steam pressure 
must be greater than the counter-pressure; so in all 
cases in which power is produced in any species of 
caloric engine, there must be a difference of tempera- 
ture between the source of heat and the atmosphere or 
condenser. The amount of this difference will deter- 
mine the amount of power, up to a certain limit, which 
a unit of heat will generate in any given engine. But, 
as the mechanical equivalent of the heat consumed in 
heating one pound of water to 1 deg. Fahrenheit would, 



68 THE USE OF THE 

if utilized without loss, raise a weight of 772 pounds 
one foot high, 'it will follow that in no engine can a 
greater performance be obtained than this, whatever 
difference of temperature we may assume between the 
extremes of heat and cold. A weight of 772 pounds, 
raised one foot high for 1 deg. Fahrenheit thermometer, 
is equivalent to 1389.6 pounds raised one foot for 1 deg. 
Centigrade thermometer ; but for convenience the term 
foot-pound is very generally employed to denote the 
dynamical unit, or measure of power expressed by a 
weight of one pound raised one foot high. A horse- 
power, an actual or indicated horse-power, is a dynami- 
cal unit, expressed by 33,000 pounds raised one foot 
high in one minute — or 550 foot-pounds per second, 
33,000 foot-pounds per minute, 1,980,000 foot-pounds 
per hour. This unit takes into account the rate of work 
of the machine. 

HEAT. 

There are three forms of heat— Sensible Heat, Latent 
Heat, and Specific Heat. 

Sensible Heat — Is heat that is sensible to the touch, 
or measurable by the thermometer. 

Latent Heat — Is the heat which a body absorbs in 
changing its state from solid to liquid, and from liquid 



STEAM-ENGINE INDICATOR. 69 

to aeriform, without any rise of temperature ; or it is 
the heat absorbed in expansion. 

Specific Heat — Is an expression for the relative quan- 
tity of heat in a body, as compared with that in some 
other standard body of the same temperature. There 
is a constant tendency in hot bodies to cool, or to trans- 
fer part of their heat to surrounding colder bodies ; and 
contiguous bodies are said to be of equal temperature 
when there ceases to be any transfer of heat from one 
to the other. 

The most prominent phenomena of heat are, expan- 
sion, liquefaction, and vaporization. 

DIFFERENCE BETWEEN TEMPERATURE AND QUANTITY 

OF HEAT. 

It is evident that two pounds of boiling water have 
just twice as much heat in them as one pound ; but it 
does not follow, nor is it the case, that two pounds of 
boiling water, at 212 deg. , contain twice the quantity of 
heat that is contained in two pounds of water at 106 
deg. Experiment shows, that when equal quantities of 
water, at different temperatures, are mixed together, the 
resulting temperature is a mean of the two. Thus, if a 
pound of water, at a temperature of 200 deg., be mixed 
with a pound of water at 100 deg. , we have two pounds 



70 THE USE OP THE 

of water resulting therefrom at a temperature of 150 
deg. But, before we could suppose that a pound of 
water at 200 deg. has twice the quantity of heat in it 
that one pound has at 100 deg., it would be necessary to 
conclude that water at deg. , or zero, has no heat in it 
whatever. This is by no means the case, as tempera- 
tures much below zero have been experimentally arrived 
at, and even naturally occur in northern latitudes. One 
pound of ice, at a temperature below zero, rises in tem- 
perature by each successive addition of heat, until it 
attains the temperature of 32 deg. when it begins to 
melt; and, notwithstanding successive additions being 
made to its heat, its temperature refuses to rise above 
32 deg. until liquefaction has been completed. As soon 
as all the ice has been melted, the temperature of its 
water will continue to rise with each successive increase 
of heat, until the temperature of 212 cleg, has been 
reached, when the water will boil, and all further 
additions to the heat will be expended in evaporating 
the water or in converting it into steam. Although a 
pound of water, in the form of steam at atmospheric 
pressure, has only the same temperature as a pound of 
boiling water, it has a great deal more heat in it, as is 
shown by the fact that it will heat to a given tempera- 
ture a great many more pounds of cold water than a 
pound of boiling water would. 



STEAM-ENGINE INDICATOR. 71 

ABSOLUTE ZERO. 

The foregoing considerations lead naturally to the 
inquiry whether, although bodies at the zero of Fahren- 
heit's scale are still possessed of some heat, there may 
not, nevertheless, be a point at which there would be 
no heat whatever, and which point constitutes the true 
and absolute zero. Such a point has never been practi- 
cally arrived at. But the law of elasticity of the gases, 
and their expansion by heat, leads to the conclusion 
that there is such a point, and that it is situated 461.2 
deg. Fahrenheit below the zero of Fahrenheit's scale, or 
that it is - 461.2 cleg. Fahrenheit - 274 deg. Centigrade, or 
-219.2 deg. Reaumur. Prof. Eankine has shown that, 
by reckoning temperatures from this theoretical zero, 
at which there is supposed to be no heat and no elas- 
ticity, the phenomena dependent upon temperature are 
more readily grouped and more simply expressed than 
would otherwise be possible. 

FIXED TEMPERATURES. 

The circumstance of the temperatures of liquefac- 
tion and ebullition being fixed and constant, enables us 
to obtain certain standard or uniform temperatures to 
which all others may easily be referred. One of these 
is the melting point of ice, and another is the boiling 
point of pure water under the average atmospheric 



72 THE USE OF THE 

pressure of 14.7 pounds on the square inch> or 2116.8 
pounds on the square foot, or under the pressure of a 
vertical column of mercury 29.922 inches (practically 30 
inches) high, the mercury being at the density proper to 
the temperature of melting ice. 

THERMOMETERS — HEAT TO MEASURE. 

Thermometers measure temperatures by the expan- 
sion which a certain selected body undergoes from the 
application of heat. Sometimes the selected body is a 
solid, as a rod of brass or platinum ; sometimes a liquid, 
as mercury or spirits of wine ; sometimes gas, air, or 
hydrogen. In a perfect gas the elasticity is in propor- 
tion to the compression, whereas in an imperfect gas — 
such as carbonic acid, which may be condensed into a 
liquid — the rate of elasticity diminishes as the point of 
condensation is approached. Every gas approaches 
more nearly to the condition of a perfect gas the more 
it is heated and rarefied, but an absolutely perfect gas 
does not exist in nature. Common air approaches suf- 
ficiently to the condition of a perfect gas to be a just 
measure of temperatures, by its expansion. Air and all 
other gases expand equally with equal increments of tem- 
perature ; and it is found experimentally that a cubic 
foot of air, at the temperature of melting ice, or 32 deg., 
will form 1.365 cubic feet of the same pressure at the 



STEAM-ENGINE INDICATOR. 73 

temperature of boiling water, or 212 deg. Thermome- 
ters are not generally constructed with air as the ex- 
panding fluid, except for the measurement of very high 
temperatures. The most common kind of thermome- 
ters consist of a small glass bulb filled with mercury, 
and in connection with a capillary tube. The ther- 
mometer commonly used in this country is Fahrenheit's 
thermometer, of which the zero, or 0, of the scale is fixed 
at the temperature produced by mixing salt with snow ; 
and which temperature is 32 deg. below the freezing- 
point of water. The Centigrade thermometer is that 
commonly used on the continent of Europe ; and it is 
graduated by dividing the distance between the point 
where the mercury stands at the freezing-point of 
water and the point where it stands at the boiling- 
point of water, into 100 equal parts. On this ther- 
mometer the zero is at the freezing-point of water. 
Another thermometer, called Reaumur's, has its zero 
at the freezing-point of water, and the distance be- 
tween that and the boiling-point is divided into eighty 
parts. Hence, 80 deg. Reaumur are equal to 100 deg. 
Centigrade and 180 deg. Fahrenheit. Water, in com- 
mon with melted cast-iron, melted bismuth, and va- 
rious other fluid substances, the particles of which 
assume a crystalline arrangement during congelation, 
suffer an increase of bulk as the point of congelation 



74 THE USE OF THE 

is approached, and expands in solidifying. But as 
soon as any of these substances become solid, it then 
contracts with every diminution of temperature. 
Water, in freezing, bursts by its expansion any vessel 
in which it may be confined, and ice, being lighter 
than water, floats upon water. So, also, for the same 
reason, solid cast-iron floats on melted cast-iron. The 
point of maximum density of water is 39.1 deg. Fah- 
renheit, and between that point and 32 deg. the bulk 
of water increases by cold. A cubic foot of water at 
32 deg. weighs 62.425 pounds, but a cubic foot of ice 
at 32 deg. weighs only 57.5 pounds. There is, conse- 
quently, a difference of nearly 5 pounds in each cubic 
foot between the weight of ice and the weight of 
water. 

COMPRESSION AND EXPANSION OP GASES. 

When a gas or vapor is compressed into half its 
original bulk, its pressure is doubled ; when com- 
pressed into one-third of its original bulk, its pressure 
is trebled; when into one-fourth, it is quadrupled; 
and generally the pressure varies inversely as the 
bulk into which the gas is compressed. So if the 
volume is doubled the pressure is made one-half of 
what it was before — the pressure being in every case 
reckoned from 14.7 pounds below the atmosphere, or 



STEAM-ENGINE INDICATOR. 75 

from a perfect vacuum. Thus, if we take the aver- 
age pressure of the atmosphere at 14.7 pounds on the 
square inch, a cubic foot of air, if allowed to expand 
twice its 'bulk by being placed in a vacuum measur- 
ing two cubic feet, will have a pressure of 7.35 pounds 
above a perfect vacuum, and also of 7.35 pounds be- 
low the atmosphere; if the cubic foot of air be com- 
pressed into a space of half a cubic foot, the pressure 
will become 29.4 pounds above a perfect vacuum and 
14.7 above the atmosphere, or will be equal to a 
pressure of two atmospheres. This law was first in- 
vestigated by a Frenchman, by the name of Mariotte, 
and is called Mariotte's law of gases. A cubic foot 
of air at 32 deg. becomes 1.365 cubic feet at 212 deg., 
the pressure remaining constant; or if the volume be 
kept constant, then the pressure of one atmosphere 
at 32 deg. becomes 1.365 atmospheres, or a little over 
1$ atmospheres at 212 deg. These two laws, which 
are of the utmost importance in all physical re- 
searches, it is necessary fully to understand and re- 
member. The rates of expansion and compression 
for each gas are not precisely the same, but the de- 
parture from the law is small and need not be dis- 
cussed here. 



76 THE USE OF THE 

LIQUEFACTION. 

Solidity is an accident of temperature, for there is 
reason to believe that there is no substance in nature 
that cannot be melted and even vaporized by the ap- 
plication of powerful heat. There are two incidents 
attending liquefaction that are important: The first 
is, that the liquefaction of the same substance always 
takes place at the same temperature, and the melt- 
ing-point can be used as an index of temperature. 
The second is, that during liquefaction the tempera- 
ture remains fixed, the accession of heat which has 
been received during the process of liquefaction being 
consumed or absorbed in accomplishing the liquefac- 
tion, or, in other words, it has become latent. This 
heat is given out again in the process of solidification. 
Water deprived of air, and covered with a thin film 
of oil, may be cooled to 20 deg. or 22 deg. below the 
freezing-point ; but on solidification the temperature 
will rise to the freezing-point. Each substance has, 
under ordinary circumstances, its own melting-point ; 
ice melting at 32 deg., and in melting absorbs as 
much heat as would raise the temperature of the 
same weight of water 142.65 deg., or as would raise 
142.65 times that weight of water one degree; but, 
notwithstanding this accession of heat, the ice, during 
liquefaction, does not rise above 32 deg. If the heat 



STEAM-ENGINE INDICATOR. 77 

employed to melt ice was applied to heat the same 
weight of ice-cold water, it would heat it to the tem- 
perature of 174.65 deg., or 142.65 deg. added to 32 deg. 
the heat of the water when the heat was first applied. 
When there is no external source of heat from which 
the heat which becomes latent in liquefaction can be 
derived, and the circumstances are, nevertheless, such 
as to cause liquefaction to take place, the heat which 
becomes latent is derived from the substances them- 
selves, and correspondingly lowers their temperature. 
Thus, when snow and salt are mixed together, the 
snow and salt are dissolved ; but as in melting they 
absorb heat, and as there is no external source from 
which the heat is derived, the temperature of the 
mixture falls very much below that of either of the 
substances before mixing. So, also, when saltpetre and 
other salts are dissolved in water, cold is produced; 
and on this principle the freezing mixtures are com- 
pounded which are employed to produce artificial cold 
in warm climates. 

VAPORIZATION, 

The first phenomenon of the application of heat 
to a solid substance is to expand it, the next to 
melt it, and a further application converts it from 
a liquid into a vapor or gas. The point at which 



78 THE USE OF THE 

increase of heat, instead of raising the temperature, 
is absorbed in the generation of vapor, is called the 
boiling-point of the liquid. Different liquids have 
different boiling-points under the same pressure, and 
the same liquid will boil at a lower temperature in a 
vacuum, or under a low pressure, than it will under 
a high pressure. As the pressure of the atmosphere 
varies at different altitudes, liquids will boil at differ- 
ent temperatures at different altitudes, and the height 
of a mountain may be approximately determined by 
the temperature at which water boils at its summit. 
Yapors are saturated gases, or gases are vapors sur- 
charged by heat. Steam is the saturated vapor of 
water, or it is a thin, elastic, invisible fluid that water 
is converted into by the continued application of heat; 
and if any of the heat be withdrawn from it, a por- 
tion of the water is precipitated or condensed. That 
which is generated, after the boiling-point is reached 
and the water is in ebullition, is called steam ; and 
that which is formed below the boiling-point, while 
the surface of the water is quiet, is called vapor — a 
distinction with a very slight difference. Surcharged 
or superheated steam resembles gas in its qualities, 
and a portion of the heat may be withdrawn from it 
without producing the precipitation of any part of its 
constituent water. Hence the importance of super- 



STEAM-ENGINE INDICATOR. 79 

heating steam, and carrying the heat up above the 
temperature due to that pressure; then, what heat is 
lost by radiation, as the steam passes through the 
pipes to the cylinder, can be spared from it without 
any condensation taking place, and the steam enter- 
ing the cylinder will not carry much water with it. 
The writer believes that surcharged steam is also re- 
sponsible for explosions in many instances. Some 
people will maintain that water in a steam-boiler never 
boils ; but every one will agree with me that water 
boils in an open vessel, and, consequently, under a pres- 
sure of one atmosphere, and to that pressure is due (if 
the water is fresh) 212 deg. of sensible heat, and 
when two atmospheres of pressure are reached there 
is due to that pressure a temperature of about 250 
deg. Now, when this temperature and pressure are 
reached, and the heat is properly distributed alike 
through the mass of steam and water, the water will 
boil just as certainly as it does under one atmos- 
phere, or in an open vessel where all may see. And, 
as in an open vessel, if the heat becomes exces- 
sive, the pressure remaining constant, the water 
will boil more violently, so, under a pressure of 
two atmospheres, in a closed vessel, if the heat ex- 
ceeds what is due to that pressure, the water will boil 
violently, and if the heat falls below what is due to 



80 THE USE OP THE 

that pressure, then the steam-pressure preponderates 
and holds the water down as it were, and the ebulli- 
tion ceases until the heat recovers or the pressure 
falls. What is true of one or two atmospheres is 
true of all pressures. This is one cause of priming, 
which occurs, as all steam-engineers know, most fre- 
quently upon engines whose boilers have too little 
steam-room, and when the water is high in the boiler, 
thus reducing the steam-room to its minimum and the 
engine is running fully loaded, and making large de- 
mands for steam upon the boiler, the pressure is there- 
by reduced below what is due to the temperature and 
the conseqence is very violent ebullition, so much so 
that the water is carried over into the cylinder at 
every pulsation of the engine and sometimes out of 
the safety-valve. I have seen the water priming twenty 
feet high out of a safety-valve pipe. Does any one 
suppose the water in that boiler was not boiling ? 
So far, we have considered more particularly excess 
of heat in the water, now let us look at excess of 
heat, under certain conditions, in the steam. To su- 
perheat steam for useful purposes which have been 
mentioned, it should be done in a vessel or some por- 
tion of the generator somewhat (though slightly) 
removed from the water; or steam from several boil- 
ers may be made to pass through one common super- 



STEAM-ENGINE INDICATOR. 81 

heater on its way to the engine, thus being entirely 
removed from the generators, which is doubtless the 
best way. But suppose we have superheated or sur- 
charged steam in an ordinary cylindrical boiler, the 
heat in the water is not up to what is due to the 
pressure of the steam and the surface of the water 
ceases ebullition. This may occur from stopping the 
engines, thereby suddenly raising the pressure, and 
perhaps at about the same time fresh coal has been 
put upon the fire, which aids in lowering the tem- 
perature just as the pressure from the previous cause 
is increasing. The foregoing will be seen to be an 
anomalous but by no means an impossible condition 
of affairs. Now, suppose the fire-line on the boiler- 
side is high and the water low, the steam receiver 
additional heat, making matters worse, until it be- 
comes excessively dry, dessicated, or surcharged steam,, 
the appearance of which, if the upper water-gauge 
was opened, would be very blue — more resembling^ 
gas than steam — and in this condition it is perfectly 
harmless; it has not the tension of steam at much, 
lower temperature, but it has a great excess of heat.. 
Now, how can an explosion occur ? Start the engine,, 
and the steam commences to move off; circulation of 
the water commences, and every particle of this 
harmless dry steam at once seizes upon all the water 



82 THE USE OF THE 

it can take up, suddenly becoming ordinary steam of 
somewhat less temperature, but enormously increased 
in density and pressure, with what effect upon the 
boiler depends entirely upon the strain it is capable of 
bearing without rupture. Suppose the heating of the 
side in contact with the steam to have reached 400 deg. ; 
fully saturated steam, at this temperature, will assume a 
pressure of about 215 pounds per square inch above the 
atmosphere — a pressure quite equal to account for many 
of the disastrous explosions on record. Many steam- 
boats have stopped at a wharf, and been started 
away again only to make a very few revolutions and 
explode their boilers, scattering destruction on every 
side. Stationary engines, too, in many instances, have 
had their boilers explode just after starting in the 
morning, or in the afternoon; and these explosions 
are marked with a violence akin to "nitro glycerine" 
Juries of inquest talk about gas and low water, when 
the explosion has been reached by a series of perfect- 
ly natural causes. It is true the water has been low, 
but quite possibly not below the lower gauge at any 
time; and when the engineer, if he is living, trem- 
blingly testifies, that before starting the engine he 
tried his water and found a full gauge at the lower 
■cock, and again after starting in the brief interval 
that elapsed before the catastrophe, he tried it again, 



STEAM-ENGINE INDICATOR. 83 

and found water at the second gauge, and perhaps the 
third, he tells the sacred truth. But nine or more of 
those gas jurymen don't believe him. They say his 
nerves are affected, and he is desirous of screening 
himself; and of course no one else tried the gauges 
but him to disprove his statement. "But it must be 
low watery The very violence of the explosion proves 
that the boiler was perfectly sound, and the verdict is 
brought in accordingly : " Explosion caused by low 
water." It is best to provide for superheating with- 
out carrying the fire-line too high, and to have the 
water and steam-room in proper proportions, and to 
raise the safety-valve when getting up steam in the 
morning, and see that it raises at proper intervals if 
the engine is standing still for any length of time, 
however brief, and especially if canying very high 
pressure. If the engine is standing still long at high 
pressure and the safety-valve does not blow, something 
is wrong. A boiler should not be left, when it is not 
doing any work, to superheat its steam and get all 
ready to go off the moment it is touched. 

EXPANSION OF STEAM. 

Under the head of compression and expansion of 
gases (page 74), the general law controlling compres- 
sion and expansion was considered, and the same law 



84 THE USE OF THE 

holding good for the expansion of steam, let us exam- 
ine its practical utility in the steam-engine. When 
air is compressed into a smaller volume, a certain 
amount of power is expended in accomplishing the 
compression, which power, as in the case of a spring, 
is given back again when the pressure is withdrawn. 
If, however, the air, when compressed, is suddenly- 
dismissed into the atmosphere, the power expended 
in compression will be lost, and there is a loss of 
power, therefore, in dispensing with that power which 
is recoverable by the expansion of the air to its orig- 
inal volume. Now, the steam in the boiler is in the 
condition of air already compressed, say to 60 or 75 
pounds pressure, shall we wire-draw it down to 20 or 
30 pounds to the cylinder, and thereby lose 50 to 75 
per cent, of its power, or shall it be let into the 
cylinder at boiler-pressure, and cut off ? The writer 
indicated an engine within the week this was written 
where the boiler-pressure was 75 pounds, and only 30 
pounds was obtained in the cylinder. Unless the 
steam is worked expansively in the cylinder — which 
is done by stopping the supply from the boiler before 
the stroke is closed — there will be a loss of a certain 
proportion of the power which the steam would 
otherwise produce. If the flow of steam to an en- 
gine be stopped or cut-off when the piston has 



STEAM-ENGINE INDICATOR. 85 

reached the half-stroke, leaving the remainder of the 
stroke to be completed by the expanding steam, then 
the effect of that steam will be increased 1.7 times 
beyond what it would have been had the steam at 
half-stroke been dismissed without extracting more 
power from it; if the steam is cut off at one- third of 
the stroke, its mechanical effect will be increased 2.1 
times ; at one-fourth, 2.4 times ; at one-fifth, 2.6 times; 
at one-sixth, 2.8 times ; at one-seventh, 3 times ; at 
one-eighth, 3.2 times. Referring again to diagram 
'No. 12 we see by it that the steam was cut off sud- 
denly at about yJo of the stroke, and the expansion 
line is well defined and falls to 5 pounds below the 
atmospheric pressure at the point of exhaust. The 
T J"o referred to is a trifle over ^ of the stroke. Thus, 
the reader may see that in actual practice we may 
exceed the figures given above, and I have seen 75 
per cent, saving reached, as shown by the coal ac- 
counts. 

In the following tables are given the average or 
mean pressure throughout the stroke, which would 
result from a given initial pressure and given fixed 
points of cut-off. In the first table the stroke is as- 
sumed to be divided into 8 parts and in the second into 
10. The initial pressures are set down in the first 
column, and are given from 3 pounds to 20, advan- 



86 THE USE OF THE INDICATOR. 

cing by 1 pound; and from 20 to 100, advancing by 
5 pounds; and from 100 to 200, advancing by 10 
pounds. 

EXAMPLE. 

If steam be admitted to the cylinder at a pressure 
of 3 pounds per square inch, and is cut off at % of 
the stroke and expands through -J-, the average or 
mean pressure during the whole stroke will be 2.96 
pounds per square inch. In like manner, if steam at 
3 pounds pressure per square inch was cut off at i 
of the stroke, and expands through £, the average or 
mean pressure during the whole stroke would be 1.15 
pounds per square inch. 



TABLES OF PRESSURES 



WHEN USING 



STEAM EXPANSIVELY. 



THE USE OF THE 



TABLE No. 



i . 



MEAN PRESSURE OF STEAM AT DIFFERENT RATES OF 
EXPANSION. 





Average pressure in 


pounds per square inch for 


*** 






the whole stroke. 




















S s S 
















^11 


Points in the stroke at which the steam 


is cut off. 


Initi 
per 


i 


i 


1 


i 


I 


i 


i 


3 


2.96 


2.89 


2.75 


2.53 


2.22 


1.79 


1.15 


4 


3.95 


3.85 


3.67 


3.38 


2.96 


2.39 


1.54 


5 


4.95 


4.82 


4.59 


4.23 


3.71 


2.98 


1.92 


6 


5.94 


5.78 


5.51 


5.08 


4.45 


3.58 


2.31 


7 


6.93 


6.75 


6.43 


5.92 


5.18 


4.17 


2.69 


8 


7.92 


7.71 


7.35 


6.77 


5.93 


4.77 


3.08 


9 


8.91 


8.67 


8.27 


7.62 


6.67 


5.37 


3.46 


10 


9.89 


9.64 


9.19 


8.46 


7.42 


5.96 


3.85 


11 


10.88 


10.60 


10.11 


9.31 


8.16 


6.56 


4.23 


12 


11.87 


11.56 


10.92 


10.16 


8.90 


7.16 


4.62 


13 


12.86 


12.53 


11.94 


11.00 


9.64 


7.75 


5.00 


14 


13.85 


13.49 


12.86 


11.85 


10.38 


8.35 


5.39 


15 


14.84 


14.46 


13.78 


12.69 


11.13 


8.95 


5.77 


16 


15.83 


15.42 


14.70 


13.54 


11.87 


9.54 


6.16 


17 


16.82 


16.38 


15.62 


14.35 


12.61 


10.14 


6.54 


18 


17.81 


17.35 


16.54 


15.24 


13.35 


10.74 


6.93 


19 


18.70 


18.31 


17.45 


16.08 


14.09 


11.33 


7.31 


20 


19.79 


19.27 


18.37 


16.93 


14.83 


11.93 


7.70 



STEAM-ENGINE INDICATOR. 



1 1 


Aven 


age pressure in pounds per square inch for 
the wlwle stroke. 


3 1£ 


Points in the stroke at which the steam 


is cut of. 


Initi 
per 


I 


t 


t 


i 


f 


i 


* 


25 


24.74 


24.09 


22.97 


21.16 


18.54 


14.91 


9.62 


30 


29.69 


28.91 


27.56 


25.39 


22.25 


17.89 


11.55 


35 


34.64 


33.73 


32.16 


29.63 


25.96 


20.88 


13.47 


40 


39.58 


38.55 


36.75 


33.86 


29.67 


23.86 


15.39 


45 


44.53 


43.37 


41.34 


38.09 


33.38 


26.84 


17.32 


50 


49.48 


48.19 


45.94 


42.32 


37.07 


29.82 


19.24 


55 


54.35 


53.00 


50.53 


46.47 


40.83 


32.86 


21.19 


60 


59.24 


57.95 


54.98 


50.73 


44.49 


35.77 


23.08 


65 


64.16 


62.76 


59.53 


54.98 


48.35 


38.71 


25.03 


70 


69.12 


67.35 


64.00 


59.07 


52.00 


41.73 


26.97 


75 


74.00 


72.23 


68.72 


63.38 


55.73 


44.82 


28.89 


80 


79.00 


77.00 


73.21 


67.47 


59.41 


47.75 


30.08 


85 


84.00 


81.95 


77.74 


71.84 


63.17 


50.65 


32.67 


90 


89.00 


86.54 


82.38 


76.00 


66.94 


53.73 


34.63 


95 


93.95 


91.43 


86.98 


80.16 


70.52 


56.62 


36.65 


100 


98.89 


96.18 


91.47 


84.37 


74.23 


59.63 


38.45 


110 


108.65 


106.02 


100.07 


93.00 


81.82 


65.87 


42.47 


120 


118.57 


115.89 


110.19 


101.44 


89.10 


71.48 


46.21 


130 


128.46 


125.32 


119.31 


110.00 


96.55 


77.49 


50.01 


140 


138.41 


134.94 


128.13 


118.36 


104.00 


83.38 


53.98 


150 


148.10 


144.62 


137.63 


126.89 


111.63 


89.12 


57.94 


160 


158.00 


154.31 


146.42 


135.42 


118.71 


95.43 


61.85 


170 


168.00 


164.00 


155.98 


144.00 


126.31 


101.45 


65.56 


180 


178.00 


173.97 


164.89 


152.01 


133.70 


107.23 


69.23 


190 


187.89 


183.17 


174.11 


160.53 


141.42 


113.15 


73.08 


200 


197.75 


192.65 


183.43 


169.31 


148.53 


119.35 


77.12 



90 



THE USE OF THE 



TABLE No. 2. 

MEAN PRESSURE OF STEAM AT DIFFERENT RATES OF 
EXPANSION. 



■5 «i 


Average pressure in pounds per square 


inch for 










the whole stroke. 






«S do's 
S 1 ^ so 


















P s §& 




















- Points in the stroke at which the steam is 


cutoff. 


Initi 
per 


ft 


1 


ft 


10 


_5._ 
1 


4 
1 


A 


ft 


ft 


3 


2.98 


2.93 


2.83 


2.71 


2.54 


2.29 


1.98 


1.57 


0.99 


4 


3.97 


3.91 


3.78 


3.61 


3.38 


3.06 


2.64 


2.09 


1.32 


5 


4.97 


4.89 


4.72 


4.52 


4.23 


3.83 


3.30 


2.61 


1.65 


6 


5.96 


5.87 


5.67 


5.42 


5.08 


4.59 


3.96 


3.13 


1.98 


7 


6.95 


6.85 


6.61 


6.32 


5.92 


5.36 


4.62 


3.65 


2.31 


8 


7.95 


7.83 


7.56 


7.23 


6.77 


6.13 


5.28 


4.17 


2.64 


9 


8.94 


8.80 


8.50 


8.13 


7.62 


6.89 


5.94 


4.69 


2.97 


10 


9.94 


9.78 


9.45 


9.04 


8.46 


7.66 


6.61 


5.22 


3.30 


11 


10.93 


10.76 


10.39 


9.94 


9.31 


8.43 


7.27 


5.74 


3.63 


12 


11.92 


11.74 


11.34 


10.84 


10.16 


9.19 


7.93 


6.26 


3.96 


13 


12.86 


12.72 


12.28 


11.75 


11.00 


9.96 


8.59 


6.78 


4.29 


14 


13.91 


13.67 


13.23 


12.65 


11.85 


10.73 


9.25 


7.30 


4.62 


15 


14.90 


14.68 


14.17 


13.55 


12.69 


11.49 


9.91 


7.83 


4.95 


16 


15.89 


15.65 


15.12 


14.45 


13.54 


12.26 


10.57 


8.35 


5.28 


17 


16.89 


16.63 


16.06 


15.36 


14.35 


13.03 


11.23 


8.87 


5.61 


18 


17.88 


17.61 


17.01 


16.26 


15.24 


13.79 


11.89 


9.39 


5.94 


19 


18.88 


18.59 


17.95 


17.17 


16.08 


14.56 


12.55 


9.91 


6.27 


20 


19.87 


19.57 


18.90 


18.07 


16.93 


15.33 


13.21 


10.44 


6.60 



STEAM-ENGINE INDICATOR. 



91 



§5 


Average pressure in pounds per square inch for 




the whole stroke. 


p SS S- 






1 1 


Points in the stroke at which the steam is cut of. 


9 
10 


8_ 
10 


7. 
10 


10 


_5_ 

1 


_4_ 
1 


3. 

10 


_2. 
1 


_1_ 

10 


25 


24.84 


24.46 


23.62 


22.59 


21.16 


19.10 


16.51 


13.04 


8.25 


30 


29.81 


29.35 


28.35 


27.11 


25.39 


22.99 


19.82 


15.65 


9.91 


35 


34.78 


34.24 


33.07 


31.63 


29.63 


26.82 


23.12 


18.26 


11.56 


40 


39.74 


39.14 


37.80 


36.14 


33.86 


30.66 


26.22 


20.87 


13.21 


45 


44.91 


44.02 


42.52 


40.66 


38.09 


34.89 


29.73 


23.48 


14.86 


50 


49.68 


48.92 


47.25 


45.18 


42.32 


38.32 


33.03 


26.09 


16.51 


55 


54.38 


53.73 


52.01 


49.91 


46.47 


42.08 


36.67 


28.57 


18.12 


60 


59.45 


58.56 


56.63 


54.41 


50.73 


45.98 


39.23 


31.02 


19.79 


65 


64.35 


63.43 


61.35 


58.96 


54.98 


49.89 


42.98 


33.84 


21.49 


70 


69.33 


68.25 


66.01 


63.25 


59.07 


53.52 


46.22 


36.43 


23.18 


75 


74.29 


73.18 


70.08 


68.00 


63.38 


57.36 


49.53 


39.00 


24.72 


80 


79.18 


78.00 


75.41 


72.45 


67.47 


61.13 


52.88 


41.66 


26.41 


85 


84.13 


82.98 


80.07 


77.00 


71.84 


65.00 


56.14 


44.08 


28.02 


90 


89.11 


87.86 


85.00 


81.47 


76.00 


68.83 


59.43 


46.89 


29.69 


95 


94.08 


92.79 


89.64 


86.00 


80.16 


72.68 


62.81 


49.37 


31.34 


100 


99.08 


97.65 


94.25 


. 90.57 


84.37 


76.47 


,66.01 


52 00 


33.03 


110 


109.07 


107.54 


104.00 


99.95 


93.00 


84.12 


72.97 


57.46 


36.41 


120 


118.89 


117.35 


103.45 


108.63 


101.44 


91.98 


79.44 


62.50 


39.77 


130 


128.85 


126.89 


122.65 


117.89 


110.00 


99.47 


86.00 


67.85 


43.01 


140 


138.79 


136.53 


132.03 


126.77 


118.36 


107.21 


92.51 


73.00 


46.32 


150 


148.71 


146.28 


141.98 


136.00 


126.89 


114.56 


99.04 


78.11 


49.73 


160 


158.55 


156 13 


150.87 


145.02 


135.42 


122.37 


105.89 


83.33 


52.95 


170 


168.45 


166.00 


160.76 


154.00 


144.00 


130.10 


112.35 


88.49 


56.22 


180 


178.23 


175.81 


170.01 


163.03 


152.01 


137.85 


119.05 


93.85 


59.57 


190 


188.15 


185.72 


179.61 


172.00 


160.53 


145.54 


125.95 


98.95 


62.95 


200 


198.06 


195.10 


188.73 


181.52 


169.31 


152.82 


132.02 


104.02 


66.02 



92 THE USE OF THE 

CUTTING OFF STEAM. 

There are a great variety of expansion-valves and 
arrangements for cutting off steam, but the writer 
proposes to let the owners of these different machines 
explain their points of excellence for themselves, and 
still adheres to the rule laid down on page 11 — of 
avoiding personalities, as well in speaking of engines 
that are good as in describing those which are bad. 
The writer wishes it to be distinctly understood that 
he has no interest in the success or failure of any 
particular engine, but will recommend to users of 
steam-power such engines as will show the best dia- 
grams, according to the principles previously laid 
down, and that combine these good qualities, with 
an ability to wear well, and that do not, under ordi- 
nary circumstances, require too much attention ; in 
other words, the requisites of a first-class engine are, 
strength, simplicity, and such a combination of prin- 
ciples as will give a first-class result, in point of 
economy of fuel, which last can only be shown by 
the application of the Indicator. A tendency not to 
wear well will show itself to any observer, particularly 
after the machine is running, if it breaks some of its 
lesser parts the first week. The economy of fuel on 
some engines may be sufficient to pay a large sum for 
repairing; for instance, if a new engine save $15,000 



STEAM-ENGINE INDICATOR. 93 

worth of coal in one year, and costs $1,000 to keep 
the valve gear in good repair, the credit to the new 
engine would still be $14,000 over the old one. All 
these points need to be thoroughly considered before 
condemning a new engine that has perhaps failed in 
some minor points sooner than was expected. 

THE SLIDE-VALVE. 

As is well known, the slide-valve is the simplest 
form of valve gear that has been devised; but an 
engine with this on needs very peculiar conditions to 
work with the best economy. For this purpose it 
needs a uniform load, a uniform pressure of steam, 
and perfect adaptation to its load, in point of size, so 
that it can be run without throttling. For example 
of a slide-valve working badly, in point of economy, 
take diagram No. 2, where the engine was much too 
large for its load. The average pressure on this dia- 
gram being less than 16 pounds, while at the same 
time there was 62 pounds pressure in the boiler. 
Thus you see the steam was got up to 62 pounds 
and down again to 16, when it was used, which pro- 
cess appears to be very much like walking up a 
hill and then walking down again without any defi- 
nite purpose. Of course all the heat that was ex- 
pended in raising that steam above 16 pounds was 



94 THE USE OF THE 

lost when it came down again, as has been explained 
on page 84. But the conditions above named are 
scarce ever met with in stationary engines, although 
they may sometimes be found nearly on propellers or 
locomotives, where the engine can work right up to 
its full capacity. In such cases their relative econ- 
omy is better, or their consumption of fuel per horse- 
power per hour is less than when the engine is only 
one-quarter, one-third, or one-half loaded, and the 
steam has to be raised to a high pressure in order to 
get a sufficient quantity of it, and then wire-drawn 
down again in order to use it. As a cut-off appa- 
ratus the slide-valve on stationary engines that are 
throttled is very inefficient ; for example see again 
diagram No. 2, where the slide-valve was closed by 
lap at -!% of the stroke, the point of closure cannot 
be made out on the diagram, and it is nearly or quite 
immaterial with reference to the final result whether 
the valve closed at this point or not. But, as in the 
cases that have been named of full loaded engines,. 
the slide-valve may be made use of to cut off to 
advantage as short as f- the stroke, some say J stroke,, 
but this necessitates a balance-valve as the travel has- 
to be considerable. There are many other devices 
for cutting off steam, many of them good, but all 
subject to criticism, but this is not the place to enter 



STEAM-ENGINE INDICATOR. 95 

upon a discussion of their merits. If the general 
reader has followed me through this volume I trust 
he has added somewhat to his store of information 
upon the subject of steam ; and if my reader is a 
party owning and using steam-power, who is desi- 
rous to economize in his fuel bills, this volume tells 
what has been done by the author in a few instances, 
in his own practice, many more of which can be fur- 
nished on application. That there is a chance for 
economy on a large majority of the engines of the 
present day, there is no room to doubt; and to the 
student of mechanical engineering, and to professors 
in technical schools and colleges, or others into 
whose hands this volume may fall, I would state 
that it has been the writer's pleasure on one occasion 
to take Indicator diagrams for the benefit of the 
graduating class of a technical institute, and I take 
this opportunity of saying, that I will respond to 
institutions or individuals with pleasure, for a similar 
service in imparting practical knowledge of " the use 
of the Steam-Engine Indicator" 



DIAGRAM No. I. 




DIAGRAM No. 2. 




DIAGRAM No. 3. 




DIAGRAM No. 4. 




DIAGRAM No.«. 



DIAGRAM No. 6. 




DIAGRAM No. 8. 




DIAGRAM No. 9. 




DIAGRAM No. 10. 




o 




DIAGRAM No. 12. 




CO 



< 




DIAGRAM No. 14. 




«o 



(5 



I 


p 


n 


■ 


Hid 


■ 


Mil 


■ 


mi 


■ 


Mil 


■ 


llll 


hi 


mi 


P 


nil 


pi 


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|^^_ 


■■ 





EDWARB KMAH, 

Constructing Engineer and Draughtsman, 

NEW HAVEN, CONN., 

Publisher of "The Use of the Steam Engine Indicator;" "The 

American Standard of Bolts and Nuts" (Chart); ".Lyman's 

Gear Chart;" and "Lyman's Universal Screw Cutting 

Index, with Rule for Compound Gearing;" 

PREPARES 

Working Drawings, Plans, and Estimates for Machinery of 

various kinds, such as Steam-engines, Machinist's Tools, 

Automatic Machines, Rolling Mills, and Rolling Mill 

Machinery, for Merchant Bar Iron or Steel, or Iron 

and Steel Rails, Furnaces for Heating in Mills, 

either Common Heating, Puddling Furnaces, 

or Gas Furnaces, and will Superintend the 

Construction and Erection of any of 

the above if desired. 

Also, makes a Specialty of 

INDICATING STEAM-ENGINES, 

and respectfully solicits the patronage of Steam-engine owners, 
and, if employed, will make a full examination and report upon 
the condition of the engine, the total power expended, the amount 
of power used by tenants, if any, the power required to drive any 
given machine or set of machines, the relative economy, the set- 
ting of the valves, etc., etc., and will point out any defects of 
original construction that may appear, or damage which may have 
crept in unawares, by wearing of the parts or by accident, caus- 
ing a waste of fuel. 

Address, 

EDWARD LYMAN, C. E., 

New Haven, Conn. 
129 



THE ENGINEER'S SLIDE-RULE. 



This is a first-class reliable two-foot Rule, which extends to- 
measure three feet. It is also a calculating instrument of high 
merit. By iis use, with a little study of the book referred to 
below, any intelligent mechanic or other person may readily solve 
all questions in 

Multiplication and Division, Rule of Three, Square and Cube 
Root, Areas and Circumferences of Circles, Speeds of 
Shafting, Pulleys, and Gearing, Horse-power of Steam- 
engines and Steam-boilers, and all other ordinary 
mathematical questions. 

Price, $1.50. 

TREATISE ON THE SLIDE-RULE. 

This is a most excellent book for self-instruction in the use 
of the 

SLIDE-RULE, 

a book of over 150 pages, containing full explanation of the 
Rule, with rules and a large number of examples, and the answers 
given, so that any person may readily correct himself by them. 

Questions solved by this Rule are done instantly, when the 
method is understood, making an immense saving in time to any 
engineer or mechanic having any calculations to make. 

Ten questions can be solved by any person skilled in the use 
of the Slide-rule quicker than one can be done by the most edu- 
cated mathematician in the ordinary way. 

Price, $1.25. 

Either or both of the above sent by mail, postage prepaid, to> 
any part of the United States, on receipt of price. 
Mathematical questions worked out for any party on application. 

EDWARD LYMAN, C. E., 



Neio Have?i ) Conn. 



130 



THE AMERICAN STANDARD 



OF 



BOLTS AND NUTS. 



This is a full-sized drawing of a System of Bolts and Nuts, as 
recommended by the Franklin Institute of Philadelphia, Dec. 
15, 1864, and adopted by the United States Navy in May, 1868. and 
has been largely adopted by the leading machine shops in the 
country, and promises to become fully adopted by every one desir- 
ous of having standard work. 

This drawing shows all the Bolts in the system from % inch 
diameter to 3 inch diameter, with the heads and nuts all drawn full 
size, and the following dimensions on each Bolt, all in their proper 
places, viz. : 

The Diameter of the Bolt, 

The number of Threads to the inch. 

The width, or short diameter of the Head and Nut. 

The long diameter, or length across the corners of the Head and 

Nut. 
The length of one side of the Hexagon Head and Nut. 
The thickness of the Head. 
The thickness of the Nut. 
The diameter of the hole in the Nut, when bored for tapping. 

Also, 

an enlarged section of the form of Thread recommended, with the 
given angle. 

THESE DRAWINGS 

are all made on good drafting paper, and are calculated to with- 
stand service in the shop. 

It is a very valuable and useful drawing, and one needed by 
every machine shop and machinist. 

Price, $1.00. 

Sent by mail, postage prepaid, on receipt of price. 
Address, 

EDWARD LYMAN, C. E., 

New Haven, Conn. 
131 



THE EDDY VALVES. 

DOUBLE GATE BALL STOP VALVES, 



FOR GAS, WATER, AND STEAM. 



Fig. 1 



Fig. 2 





Fig. 1 represents the 
Ball Valve from ^ in. 
to %}£ in. inclusive. 



Fig. .2 is a represen- 
tation of a Sectional 
view of the Ball valve. 
B and C are the Disks 
or Gates, A is the Ball 
or Nut, E is the Stem, 
F is the Gland Ring. 
The Disks are shown 
closed against the 
Seats. 

THESE VALVES ARE SUPERIOR TO ANY IN THE MARKET/ 

They are double-faced, and constructed with two seperate Disks, 
each independent of the other. The Gales or Disks are pendent on 
the Ball or Nut, the Seats being divergent and not parallel, the 
Disks act as a wedge, and the Ball being forced into a correspond- 
ing recess on the back of the Gates make the wedge doubly power- 
fufin pressing and holding the Disks against the Seats. The Ball 
or Nut is constructed with trunnions on opposite sides which fit 
loosely into corresponding cavities in the Disks, thus permitting 
the Ball to start first, and relieving the Disks from pressure before 
they slide on the seats, and thereby preventing wear on the faces 
of the Disks and Seats. The Stem also rotates without rising, 
thus requiring no extra room for working. 

These valves are made strong and durable, all the parts being 
interchangeable, and have been working regularly under a hydrau- 
lic pressure of 350 to 400 pounds to the square inch, and gave good 
satisfaction. 

Send for circular and price list. 
Address, 



GEORGE W. EDDY, 

Waterford, Saratoga County, N~. Y. 
132 



LYMAN'S GEAR CHART. 



This Chart contains full directions for laying out the form of 
the Teeth of Gear Wheels, on the odontograph principle of Prof. 
Willis, both single and double curves, and a diagram of a practi- 
cal odontograph and an odontograph scale, with full-sized illustra- 
tions of the method of laying out Single and Double Curved Teeth 
in Wheels and Racks. 

ALSO, A 

GEAR SCALE, 

for proportioning the Teeth of Wheels, arranged in accordance 
with the best 

AMERICAN PRACTICE. 



ALSO, A 

RULE FOR REDUCING DIAMETRAL PITCH 
TO CIRCUMFERENTIAL, 

with a table of the principal Diametral Pitches, and their corres- 
ponding length on the Circumferential Pitch line, and a table of 
principal fractions of the inch, in common use, reduced to deci- 
mals and to one-hundredths of an inch. 

This Chart contains sufficient information to enable any person 
of intelligence, with the aid of a pair of dividers, to lay out the 
forms of Wheel Teeth, and is fully explained in a very practical 
manner, and is the most mechanical information ever offered for 
the price. 

Price, 50 cts. 

Sent by mail, postage prepaid, on receipt of price. 

Drawings of Mill Work, Gearing, and Machinery, promptly fur- 
nished. 

Address, 

EDWARD LYMAN, C. E., 

New Haven, Conn. 
133 



MACHINIST'S TOOLS, 



The undersigned respectfully solicits orders from the public for 
any of the following Machinist's Tools : 

POWER PLANES, 

which will plane in length from 2 to 16 feet, and in highth and 
width from 16 to 42 inches. 

COMPOUND PLANERS, 

Two sizes, with strokes of 9% and 14% inches. 



48-Inch SWING JPTJILILIEY LA.THE 



SCREW-CUTTING ENGINE LATHES, 

of 18, 25, 30, 36, and 50 inch swing, with lengths to suit customers. 



MERRIMAN'S PATENT BOLT CUTTERS. 



UPRIGHT DRILLING MACHINES, 

with and without Back Gear, with Automatic Feed or without. 



BACK GEARED RADIAL DRILL. 



AXLE LATHE, 

For turning Carriage Axles, &c. 

PLANER CENTERS AND CHUCKS. 



HAND LATHES, BACK GEARED CHUCKING LATHES, 

PLAIN CHUCKING LATHES, HEADS AND RESTS, 

SLIDE RESTS, LATHE CHUCKS, &c, &c. 



All of the above of first-class construction. 

EDWARD LYMAN, C. E., 

New Haven, Conn. 
134 



S WE ET'S 

PATENT IMPROVED GAS FURNACE 

AND 

HOT-BLAST STOVE, 

For Manufacturing and Rolling Mill purposes. 

Heating Furnaces constructed on reasonable terms in any part 
of the United States. 

The economy of these Furnaces over any ordinary furnace is 
15 to 40 per cent, in fuel, also a great saving in material, as there 
is much less oxidation than there is in ordinary furnaces. 

For further information, terms, &c, 

Address, 

WILLIAM A. SWEET ? 

Syracuse, N. Y., 

or EDWARD LYMAN, C. E., 

New Haven, Conn. 

LYMAN'S 

UNIVERSAL SCREW-CUTTIE INDEX, 

With rule for Compound Gearing, with an example of the method 
of figuring the Compound Gearing worked out. 

The Universal Index shows what Gears to use to cut the 
threads from 3 to 20, with Leading Screws of 4, 5, 6 and 8 threads 
to the inch. 

Price, 10 cts. 

Sent by mail, postage prepaid, on receipt of price. 
Address, 

EDWARD LYMAN, C. E, 
New Haven, Conn. 
135 



THE USE 



OF THE 



STEAM-ENGINE INDICATOR: 

OE, 

A PRACTICAL TREATISE 

ON 

THE USE OF THE STEAM-ENGINE INDICATOR, 

BEING AN ACCOUNT OF THE AUTHOR'S EXPERIENCE IN 

THE USE OF THE INDICATOR, IN CORRECTING AND 

IMPROVING THE ECONOMICAL EFFICIENCY 

OF STEAM-ENGINES, ILLUSTRATED 

WITH NUMEROUS 

ENGRAVED DIAGRAMS, 

FROM ACTUAL PRACTICE ON STATIONARY AND MARINE 

ENGINES. 

PUBLISHED BY THE AUTHOR. 

Price, $1.00. 

Sent by mail, postage prepaid, on receipt of price. A liberal 
discount to the trade. 

Adress, 

EDWARD LYMAN, C. E., 

New Haven, Conn. 

136 



